THERE WAS A LOUD BANG, a violent crack; an explosion so loud it shook the windows a couple of miles away in the coastal town of Alvor. Three massive balls of flame rose in quick succession into the air above the ship. A helicopter hovered overhead.
“Pobres diablos! ” (Poor devils!), exclaimed a naïve bystander on the shore, thinking that it was a disaster in the making.
Meanwhile, out at sea, the hundred eyes of those privileged enough to be close to the action in a flotilla of small boats were concentrating on what was happening next.
A series of muffled explosions, accompanied by violent gushes of water all around what had been the pride of the Portuguese Navy, signalled the start of the last stage of a journey to the bottom. That journey had started when the vessel was built in Nantes, France, for General Salazar’s Portugal in 1966.
The Hermengildo Capelo F481 was a João Belo-class frigate, named after a late 19th century Portuguese explorer and naval officer who had established some of the African colonies for Portugal, helping to chart territory between Angola and Mozambique in southern Central Africa unknown to Europeans in the 1870s and ’80s.
During the 1960s, the Portuguese would have preferred to acquire British Leander-class frigates, but the British government was having none of that – though in fact the class of frigate was very similar to what the Royal Navy was using at the time.
Retired British matelots, standing and watching from the shore, were heard to wrongly assure people that it was actually a Leander-class vessel.
General Salazar, the country’s leader, was maintaining one of the last remaining Fascist dictatorships in Europe, and World War Two was still fresh in everyone’s minds.
The French were less choosy, and took the money. Identical to the Commandant Rivière-class, with extra equipment for tropical climates, four ships were ordered at a time when Portugal was still intent on defending her territories in Macau and Timor in the Far East, as well as those in Africa such as Angola and Mozambique.
Later, when the vessels were no longer needed, two were sold to the Uruguayan Navy. Another collided with a tanker during a NATO exercise and was soon scrapped.
The last remaining frigate, the Hermengildo Capelo, displaced 27,000 tonnes, was 102m long and had a beam of 12m. She had a maximum speed of almost 24 knots and a range of 7500 nautical miles.
Between 1987 and 1989 she was modernised in various ways, including installation of anti-submarine warfare equipment and infrastructure that would allow for female sailors among up to 164 crew-members. She was decommissioned in 2004.
On the day of the sinking on 15 June this year, Portuguese officialdom was out in force. Impressive high-speed patrol boats from its Navy, the coastguard and the marine police buzzed about importantly, keeping vessels laden with observers at least 500m away from the frigate.
A foreign journalist noted that with so much wonderful marine hardware, it was no wonder the country had found itself in a balance-of-payments crisis.
Unbeknown to the British journalists watching aboard the SubNauta luxury catamaran, members of the Portuguese press and TV transferred from the catamaran to one of the SubNauta’s big inflatable RIBs and were allowed to approach within 50m.
The rest of us were left feeling very jealous, and reduced to photographing events with telephoto lenses.
Geysers of water gushed upwards around the wreck as the big holes blown in the sides of the hull by the explosive charges took effect. Soon she started to settle. There was no sign of a list. The 1700 tonnes of concrete that had been added to the lower part of her hull was taking effect, and she simply lay lower in the water.
Soon the gaping holes, cut in her sides for the benefit of diver safety, were dipping below the water, and it was all over. She silently slipped below the surface before plunging, as that huge mass of metal would do once deprived of its buoyancy, and crashing to the seabed 30m below.
The Hermengildo Capelo had simply disappeared. She had been there but now she was no more. We divers knew differently.

THIS PROJECT HAD STARTED six years previously – Luis Sa Couto had a dream.
The Algarve is known for its golf courses and fabulous restaurants with the Portuguese version of tapas and adventurous menus. It’s known for its spas and its sandy beaches, but he wanted to make it a primary diving destination too.
As a very successful businessman, he had the wherewithal to try to do it. He built in Portimão the finest diving centre probably anywhere in the world.
As big as a department store, SubNauta has a showroom, lecture rooms and presentation room, a huge and over-equipped equipment room, technical diving facilities and luxurious changing rooms with showers of the standard expected in a first-class hotel.
Despite this apparent luxury, SubNauta still offers competitive prices with a two-tank dive to distant sites, complete with a surface-interval snack of a ham and cheese sandwich and hot soup or coffee, that costs only around 75 euros.
Luis has employed the services of divers such as New Zealander Grant Searancke, who some of you might have known when he was a dive guide on the liveaboards Excel and Hurricane in the Red Sea, and Gary Fox, the well-known smiling Yorkshireman who runs a technical diving centre in Helston, Cornall.
He bought two huge Tornado RIBs, one with twin inboard diesels, luxury seating and even a cabin, and a slightly smaller one driven by twin 250hp Honda outboards.
As if that wasn’t enough, he commissioned a luxurious 18m motor-catamaran that provides a very stable platform from which to dive, as well as cabins and toilet facilities. It’s one of the nicest day-boats you could imagine, and also functions as a liveaboard for three-day charters out to a remote sea-mount. Luis even got small compressors built in to give it diving autonomy.
The only problem he encountered with his plan was that, except for the cannons and anchors left from the 1759 Battle of Lagos, when the British fleet destroyed the French fleet, plus a couple of other inauspicious wrecks, the Algarve didn’t really have much on which to dive.
A little problem like that was not enough to stop a man like Luis Sa Couto. He had the contacts, and he campaigned to persuade the Portuguese government to donate a flotilla of obsolete military ships to form an underwater attraction.
It took six years of battling with bureaucracy. This was a project that had never been done before and nobody knew what or who was needed to give it the go-ahead.
Luis argued that these vessels had served the nation well and could go on serving the nation by attracting divers to the area, rather than simply being sold for their scrap value. He’s not a man to take no for an answer.
The British Government took the short-term accounting option when it came to the disposal of our own Ark Royal, which was sold for its scrap value despite a campaign to have it sunk both for the benefit of leisure divers and as a nursery for increasing fish stocks in our waters (what a pity we had no Luis Sa Couto of our own).
The Hermengildo Capelo was only one of four vessels prepared environmentally and with diver safety in mind.
The same Canadian experts who had sunk many vessels in their own waters and off the USA, as well as the Scylla, the wrecked frigate now enjoyed by so many British divers off Plymouth, took care of the project.
We were shown around the frigate by Alberto from the Underwater Museum in the marina at Portimão, the day before she was due to be sent to her watery resting-place.
The Canadians were busy installing numerous GoPro cameras that would record those last moments, as well as the explosive charges and wiring needed to set it all off, while Alberto showed us how all the internal partitioning had been removed, together with all the original installation wiring of the vessel.
Holes had been cut so that there was always a visual escape route from any part of the vessel in which a diver might find himself.
The engine-room was now a spacious and uncluttered area, but one of the engine’s pistons had been reinstalled atop the engine block.
The same went for the stern steering room, where a large wrench hung exhibition-style from the roof.
The emergency treadle electricity generators for the rudder were still in place. The formerly cluttered radio-room had had most of its equipment removed so that there was no danger of a diver getting fouled up and trapped, and only a few representative items had been left in place.
Even the helm in the wheelhouse had been moved from its protected military position to a more normal commercial-vessel location.
Of course, the vessel had been cleaned of all noxious materials such as asbestos, PCBs and hydrocarbons.

ONE TRIUMPH OVER bureaucracy had been to retain the forward-mounted gun and its remote control positions.
This was the main armament of the frigate, along with its anti-ship Exocet missiles. Because of this and the fact that explosives were supplied by the Portuguese military, the Navy oversaw the whole preparation process. We were aware of the watchful eyes of men in uniform as we toured the vessel.
When I asked Alberto how resistance to the more immediate cash benefit of scrapping the vessel had been overcome, especially in lean economic times, he pointed out that the preparation process had employed more men for a far greater time than would have been the case if the vessel had simply been cut up.
The frigate had served its nation well, and now it would continue to serve it by attracting people to see it under the sea.
The Hermengildo Capelo was the third vessel sunk in an area designated as a marine park, a no-take zone for fishermen, between the Portimao and Lagos river mouths.
The first two were sunk on the same day in October 2012. They were the 85m corvette Oliveira e Carmo and the 44m ocean patrol vessel Zambesi.
The 64m Almeido Carvalho A57A, a hydrographic research vessel, ice-breaker and ex-US spy ship donated to the Portuguese during the Cold War, was due to be sunk on 21 September.
Soon after the frigate disappeared beneath the waves, a team of naval divers surveyed the wreck where it lay, checking that all the explosive charges had successfully detonated and removing any that had not.
It was then declared safe for leisure divers, and we were among the first the go down the following morning.

I WAS SURPRISED TO NOTE that most of my fellow-divers were wearing semi-dry suits, whereas a couple of us, including Alberto and one of the SubNauta guides, had come with drysuits.
Even a couple of Brits who should have known better were wearing semi-drys. I wished I’d brought more layers of undersuit, because the water was a spine chilling 14°C, the same as one might expect on the Scylla, and the visibility was about the same too.
With two big river-mouths discharging close by, and numerous tidal lagoons along the coast, one could hardly expect the water to be clear. In fact it was a very British diving experience.
I headed down the line and was almost on top of that enormous gun before I was able to see it. Thank goodness for cameras with fish-eye lenses. Without one I would have got nothing but extreme close-up pictures.
Instead, I was able to swim around the outside of the wreck and get shots of details such as the outside gun control and command positions, as well as the gun itself.
When it came to heading inside the wreck, I realised that the exercise was slightly pointless, in that I had already photographed most of it the day before when it was still afloat.
I was merely replicating what I’d already done, but added the degree of difficulty that the poorer visibility provided.
We were too early for any marine animals to have taken up residence, and indeed the banners proclaiming the SubNauta project were still tied in place.
It was interesting to see how the tremendous impact with the seabed had bent rails and sent previously installed cabinets flying, but otherwise the wreck was much the same as we’d seen the day before, only a lot wetter.

THE DESCENT LINE WAS TIED near the gun on the bow. I made my way to the stern, where a number of large anchors and huge chains had been lashed in place during the sinking. Later a team of divers can install them so that the wreck resists being moved by winter storms.
This had been a lesson learned from the previous sinkings. The corvette had hit the seabed stern-first, severing that part of the vessel. Storms had then moved it a long way across the seabed, presumably a few inches at a time, so the two parts were now well separated.
However, a dive on the wreck of the corvette proved more productive, in that it had been submerged for nine months and was now home to numerous small fish and a few oceanic triggerfish that gathered round the masthead.
Not only that, but for some reason the visibility was much better!
Today, the Algarve has become a favourite with Brits living and holidaying abroad. Portugal has had a long association with Britain, and many locals have made it their business to learn English, so it’s a comfortable place for us to visit.
Luis pointed out that the Algarve is only really busy in the peak summer months, and that accommodation is inexpensive, yet still of high quality in both spring and autumn. He hopes that divers will make it their business to visit and do some British-style diving on the military wrecks that have been sunk for this Ocean Revival Project.

FACTFILE
GETTING THERE Budget flights to Faro.
Diving & ACCOMMODATION SubNauta, www.subnauta.pt. Hotel Tivoli Marina de Portimão 4*, www.tivolihotels.com. Pestana Alvor Atlântico Residences apartments, www.pestana.com
WHEN TO GO Summer months.
CURRENCY Euro.
PRICES SubNauta dive tours range from 180-360 euros pp for a three-night weekend including B&B hotel (3-5* options) and four dives with full equipment and nitrox (if certified). Return flights from around £70.
FURTHER INFORMATION www.oceanrevival.org/en, www.visitalgarve.pt, www.algarvepromotion.pt