Dimitri Rebikoff, an early scuba pioneer, said that when diving at night 'you must have iron nerves to avoid the feeling that there are ghosts in this strange domain'.
Looking down onto black water from the surface frightens me. It conjures up a mixture of childhood memories and incoherent thoughts about unknown and unknowable life-forms that might be out to get me.
It was on a rainy night in New Guinea, far out in the Bismarck Sea, that I first revelled in the embrace of the black space. I became part of the ink. Here was the Pacific Ocean, and me, and the night, and a myriad array of creatures that were not as blind or deaf or clumsy as me. They could sense me, avoid me, or investigate me and I would never know what impression I had made upon them.
Instead of being the curious diver peering at the creatures around me, I felt like a disembodied brain, released from the confines of my body. Like one of those 'brains in a jar' in one of the original episodes of Star Trek.
In the utter blackness, even the glass faceplate of my mask became invisible without reflections from my torch. It was the kind of blackness that induces vertigo, and I felt as though I could communicate with my buddy by thought alone. I signalled to him to switch off his torch so that we were genuinely alone in the blackness, hovering above the drop-off surrounding a seamount.
After a minute, he grew bored with this activity and annoyingly switched on his light, tapping my arm to indicate that he was returning to the reef. I hung in black space for a minute or two, glancing backwards occasionally to verify that my dive buddy was still in sight, his torch a flickering mark as he scanned the reef.
But the fear was gone, as if I had surrendered myself to the void. And I knew I wanted to visit again soon.
Peeking into the bridge of the wreck.
The sun was a massive red orb dropping low over the horizon. After watching the spectacle, I icked myself up and headed off the side of the boat. At 22m, the wreck at West Rock was experiencing the changing of the guard as the nightshift took over.
Pufferfish had already switched off and the parrotfish were just getting comfy for the night. Fusiliers and grunts were going crazy circling the wreck from keel to superstructure. It was a dazzling spectacle. Then, as the light faded, they completely disappeared.
The wreck itself was a big surprise.
I had dived the site the day before, learning of the presence of a small wreck only minutes before heading down the shot with my macro camera.
I was back tonight with my wide-angle kit to do justice to what I would call a sizeable cargo vessel, with brass running lights and portholes intact.
The wreck was fantastic in its own right, but the guests, in the form of large grouper that inhabited the cabins, made the dive very special.
Most of the grouper had abandoned themselves in weird locations all over the wreck and were sound asleep, but one massive specimen was burning the midnight oil and slipped out through a vacated porthole. Awesome!
Lesser octopus spotted by Paul Naylor on his favourite night dive.
There was still snow on the hills above Port Douglas when I arrived on the Isle of Man to visit an old friend in early March this year. I expected to spend the first evening in the pub, but was whisked off to do a night dive in Port Erin Bay while the tides were right. There was a chance, I was told, that we might see an octopus.
We saw our first octopus almost as soon as we submerged by the steps. Working along the boundary between rocks and sand, where numerous squat lobsters and crabs scuttled in our torch beams, we found five more. One had dug itself well into the sand, presumably looking for buried crabs.
Each octopus either stayed serenely in position or retreated to hunt elsewhere, moving in that wonderfully sinuous way that only an octopus can.
Fish life included plaice, topknots, a beautiful snake pipefish and a proud-looking sea scorpion.
The cold made me decide to replace my nine-year-old drysuit, and after 50 minutes my numb hands could barely operate the camera controls.
It didn't spoil my enjoyment, however, and the octopuses and other animals made this a memorable and magical dive.
I am not a great fan of night dives. Most of the time I would rather be decompressing in the pub. But every now and then I get talked into doing it. And every now and then, the night dive surpasses all expectations.
One such dive that I still remember well because it was so surprisingly good happened six years ago in the Caribbean island of Dominica, at a site called Sibouli. With no light from the land, no moon and very black volcanic sand, it was about as black as a night dive can ever get.
I spotted the first octopus within minutes of starting, and by the end of the dive I had seen five of them. In between octopus sightings, I almost bumped into a pair of flying gurnards resting on the sand, some violently fluorescent anemones, a pair of mating nudibranchs, a small member of the pufferfish family half-buried, crabs, lobsters and I forget what else, because I had already blown my film.
Add to that the nice warm water and a tropical evening with just the faintest of warm breezes coming off the land, and I didn't even need to wrap up afterwards. We even got back in time for a few beers.
As a deep UK wreck diver, I don't have much time to enjoy night dives these days. However, that doesn't mean I haven't done night dives abroad in the past.
Thinking back over the years in an effort to recall a favourite example, the one that springs to mind happened one quiet evening in the Red Sea.
We had moored up alone, close to a northern reef on a very dark but still evening. All we could see were some distant lights from a small Egyptian village. The water looked irresistible.
With my rebreather, which I had already prepared earlier in the evening, I entered the water alone and dropped to the seabed less than 10m below.
On a liveaboard it is difficult to find some space to spend a few moments alone, but now I had discovered the perfect place - the silent Red Sea.
The glimmer of the dive-boat's lights above looked impressive, penetrating the clear water. Moments later, as I fired up my HID lights, I was surrounded by several curious Indian lionfish.
Closed-circuit made the moment silent, and I cannot think of another time in my life that was so tranquil, the direct opposite to my usual choice of diving.
I spent the next two hours alone along that Egyptian reef, enjoying the creatures that appeared in my beam of light: red soldierfish, orange-striped triggerfish, slingjaw wrasse, the odd swarthy parrotfish and creatures I had never seen before!
If ever there was an answer to why we dive, this was it!
'Welcome to Israel,' said Itzhak after we had braved the strict airport security to dive in the Red Sea.
Darkness enshrouded us. Shadows looming with the latent menace of encircling hostile countries sent shivers down our spines, despite the warm evening.
First Itzhak registered our night-dive - my first overseas - with the machine-gun-toting soldiers on beach duty. 'Remember hand-signals. Only one torch each, don't wander, we don't want to be shot out of the water.
'Get your buoyancy right. Don't touch the fire coral, the pain's excruciating. Don't put your feet down; you won't see the deadly stonefish.
'Spiny sea-urchins patrol the bottom; we swim above them but below the spines of the lethal lionfish. Just follow me and enjoy an amazing dive.'
Adrenalin fizzed in our veins, part-conquering our fear of the unknown as we followed Itzhak into the velvet sea seething with unfamiliar, noxious species. The tension was unbearable as, mindful of his warnings, we copied his every move. Only our eyes swivelled endlessly from side to side.
The quiet was unnerving but the rainbow colours of the coral, highlighted by our torches, were wonderful. Sharp-toothed moray eels poked from the rocks as we passed shoals of sleeping clownfish, and wrasse.
I imagined the barracuda we had seen that morning still lurking on the reef as we dodged the innocent-looking fire coral and the venomous fin spines of the beautiful, zebra-striped lionfish, capable of causing acute pain, paralysis and death.
Gradually amazement overtook the panic and, despite my terror, I wanted my hour-long night dive to last forever.
Cruising cuttlefish, Lembeh-style.
I'm a morning person. At sunset it's time for a cold beer, not blundering around in the blackness of the undersea night. And anyway, all you ever see are the same things as on a day dive, but fewer of them.
That was my philosophy until my first night dive in the Lembeh Strait. I always wish that I could see the Strait's sea floor in cross-section to see all the critters buried there, and at dusk the daytime creatures sinking back into the black sandy seabed, with a whole new cast of strange nocturnal characters emerging to prowl the sea floor till dawn.
Small shells, giant shells, incredibly ornately structured shells, all emerge from the silty substrate to crawl across the seabed.
Stargazers lurk, big eyes alert to any fish passing overhead. Bizarre bobbitt worms emerge from the sand.
Slipper lobsters and all sorts of crabs scurry around. Some have remained buried during the day; others have simply been camouflaged - the ingenuity of the decorator crabs is astonishing.
Octopuses emerge from their daytime lairs to slide over the seabed, hunting for prey. All sorts of eels - morays, congers, snake-eels - slither purposefully, their heightened sense of smell enabling them to locate victims.
Strange nocturnal fish stalk, many with huge eyes enabling them to use even the faintest glimmer of undersea moonlight to hunt. Many are red in colour - red is the first colour of the spectrum to disappear, so their coloration is like a night-time cloak of invisibility.
And with all this activity there is always intriguing behaviour - a frogfish gorging itself on small fish attracted to the camera lights, an octopus dashing from its lair to capture a passing shrimp, cuttlefish cruising across the sand, their long tongues darting out to nail their victims...
OK, maybe all this didn't happen on just one dive, but my memories of Lembeh Strait have merged into one amazing night-time experience. Worth missing that sunset beer for!
Bull shark: a surprise night-time visitor.
Late one night off the Pacific Coast of Costa Rica, a night dive didn't go according to plan. The boat dropped us a little way from the reef, and as we descended we felt a swift current moving us further away. Suddenly we were surrounded by a massive school of yellowfin tuna. They weren't hanging around as they swirled around us, and I was sure that something big had to be chasing them.
A massive dark shape was approaching and, before I knew it, I was face to face with a huge bull shark. For what felt like an eternity but could only have been a second, I stared straight into his eyes and he into mine. He was so close,
I could have reached out and touched him. It was hard to say who was more surprised by this unexpected encounter, but with a quick flick of his tail, he was gone, chasing his prey - and I was left wondering if it had really happened.
While living in Bermuda, I was part of a small group of divers who would get together for a night dive to break up the working week.
On one sultry August evening at John Smith's Bay, we couldn't get in fast enough - a layer of cloud was holding in the heat of the day and there wasn't a breath of wind.
The only sound around us was the chirping of the tree frogs.
The dive was like most of my previous night dives at this location - until my buddy reached over and turned my torch off.
I wasn't sure what to expect next, but as my eyes got used to the ambient light around me, I realised what was happening.
The clouds had cleared, and flickering beams from the moon now filled the water column.
We didn't see half the marine life we would have seen had we had our torches on, but the ethereal illumination of the reef's gullies, overhangs and shapes provided by the moonlight provided us with a perspective we had never previously considered.
As we finned back to the shore, I became transfixed by the moonbeams dancing on the ripples in the sand.
As we surfaced, the moon's reflection stood perfectly on the surface, reaching out into the horizon. It doesn't get much better than this.
Cuttlefish in Gozo
an equally colouful flying gurnard
Xlendi Bay is an ideal place for an easy and relaxing night dive (although it does feel unusual to kit up and walk past the tables of diners at the outdoor restaurants that line the bay in order to get to the entry point!).
The sheltered bay is shallow, with a part-seagrass, part-sandy bottom and lots of colourful creatures out and about of an evening.
Among those creatures that made this dive special for me were the cuttlefish and flying gurnards. I had never seen cuttlefish before, and was thrilled to come across one gracefully swimming across my path.
As I stayed motionless, the delightful creature swam around me for a while.
Watching as it changed colour from iridescent blue/green to the colour of the ground beneath was an amazing experience. It disappeared into the blackness after a few minutes, but not before I had obtained a picture for my dive archives.
As for the gurnards, they were strutting around like peacocks, in some numbers. One, drawn by the beam of my torch, took off from the bottom and glided straight towards me, stopping only inches from my mask before turning away.
A wonderful moment captured in my memory, if not by my camera.
Tiny bobtail squid emerge from the sand by night.
Porcelain crab hides in a sea-pen
featherstars often host ornate ghost pipefish
devil scorpionfish, a hazard at night for unwary divers
Wherever you are, a night dive is a special experience, but in the tropics you can guarantee the wow factor. My favourite venue is Torpedo Alley in Horseshoe Bay at Rinca Island in the Komodo National Park.
It's always worth doing a recce dive during the day just to get your bearings and see the topography of the site.
This one has the perfect mix of a gentle dark-sand slope bordered by shallow fringing reef, providing two habitats to explore in the same dive. The site is named after the small electric 'torpedo' rays commonly seen here, particularly hunting at night, but these are only a minor attraction.
On the sand slope, check out the pastel-hued sea pens that are home to tiny colour-matched porcelain crabs, shrimps and clingfish. The sand also contains snake-eels, stargazers and inimicus scorpionfish, so it doesn't matter where you settle!
Next to one section of reef is an old tree trunk that is a magnet to ghost pipefish, decorator crabs with sponge and hydroid adornment, tiny clown frogfish, numerous shrimp species (check the featherstars) and some of the cutest bobtail squid, as well as flamboyant cuttlefish that will use your torchlight to hunt by.
The usual suspects are here - lionfish, scorpionfish - but keep your eyes peeled for something really unusual, like the Rhinopias or weedy scorpionfish sometimes found on the reef. Above all, make sure you have fresh torch batteries, and carry a spare!
Trewavas - in the dark about the appeal of night dives, despite her hare-raising experience..
I'm a night-dive refusenik! I don't do night dives. Or perhaps, more accurately, as most of my dives are in the UK at 60m or below, the experience of diving in darkness is pretty routine. After a good day's diving, the lure of bars, restaurants and socialising is a lot stronger than the urge to kit up and jump in the sea again. It's too much effort - and for what?
I've only ever bothered when I'm abroad, and even there, the sight of a few sleeping fish and those gribbly things that come out at night generally holds my interest for fewer than five minutes.
My best-ever night dive was in S'Algar, Minorca, with cave-diver and photographer Gavin Newman. The entire place was swarming with angry scorpionfish, which added a deliciously risky edge. I was laughing my head off, because I couldn't even put a finger down, and it made posing for the photos a bit of a challenge.
My buddy was photographing sea hares - giant red sea slugs that took off like flying jellies. I had them crawling up my arm and over my head. But what really made it special was diving with Gavin - night time or anytime. Frankly, I'd have enjoyed diving in a sludge bucket with that man; he's a total star.
Whitetip reef sharks hunting by night at Cocos - they really get stuck in.
I had got bored with night dives. Everything would have gone to bed, and when you did find a solitary nocturnal creature, you suffered other divers standing on your head. I would rather spend the time getting ready for dinner. That's why I did no night dives on my first visit to Cocos Island.
My wife never misses any dive. She was with me on my second visit - which is why I never missed a night dive then, or on three subsequent visits.
Manuelita Island at night. You don't need to search for anything interesting -it searches for you! The whitetip reef sharks have learned to use the lights of divers in their voracious night-time search for hapless victims.
I don't mean you get the odd predator following you along, or even a few sharks. I am talking about hundreds!
The seabed becomes a churning mass of grey bodies as they compete to catch the small fish loitering helplessly under rocks. You may have seen whitetip reef sharks lolling lugubriously on the sand during daylight hours, but at night they become every small fish's worst nightmare.
It's a spectacle. I just make sure I get my buoyancy perfect. I don't want to put an unsuspecting hand among that lot!
Capstan on the Victoria.
Diving at night is probably the most relaxing thing I can imagine doing. Ever since I started diving I have always tried to dive after sunset whenever possible, whether turtle-spotting on a Barbadian reef or trimix-diving 100m down on a wreck - it's magic.
Seeing by torchlight lets the mind focus only on an image in the spotlight, eliminating all the peripheral adverts that normally cloud and pollute life and vistas topside.
My favourite all-time night dive was last year during a trip to Lebanon. Bad weather had prevented diving on HMS Victoria for a week, but every day the winds abated by 6-7pm. We decided to dive the wreck to 100m as a night dive and it proved incredible.
Looking through a torch beam focused our gaze onto fragments of the wreck yet unnoticed. Peering through portholes and doorways, scanning the scene just a foot at a time, it was possible to draw an image of life on-board just before Victoria's tragic sinking a century ago.
Every shadow seemed to dance and play mind tricks, looking inside this gallant wreck - was it a trick of the light, a restless fish or something else? Who knows?
Just as amazing was to dive to such incredible depths at night, a group of seven divers using both open- and closed-circuit equipment, with everybody clearly having the dive of their lives.