DESCENDING ONLY A FEW metres, I could see a sandy seabed 15m below me, rippled with wave-like indentations.
Suddenly, out of nowhere, an ominous, sinuous but bulky dark body appeared, unmistakable in its shape and hugging the bottom as it swam lazily below us – a bull shark.
Gustavo, our dive-guide, signalled for us to level off in midwater and swim away from the shark, continuing our descent once it was out of view.
Kneeling calmly on the bottom at 16m, we waited for several minutes, peering into the blue around us.
We were on an observational bull-shark dive offered by Pro Dive International, one of Mexico’s leading dive-centres.
Pro Dive has nine centres located on the Yucatan peninsula, the holiday playground renowned for its white-sand beaches and turquoise waters, and incorporating the island of Cozumel.
We were using the centre at the Royal Hideaway Hotel in Playacar. With excellent facilities and a perfect location to access all the main dive-sites along the coast, Pro Dive also offers free nitrox to qualified divers. This was helpful, particularly for the bull-shark dives, conducted between 16 and 25m.
With five other divers and two other guides we had boarded Pro Dive’s boat, moored in the shallow water off the beach by the centre. A 10-minute ride north and 500m off the beach that runs along the whole coastline brought us to Shark Point, a known resting area for female bull sharks. They come every year between November and March, before and after giving birth.
Gustavo had told us as part of his comprehensive briefing that the sharks disappear for a week or two from late January to early February to give birth in fresh water, before reappearing for several weeks while they recover. They then leave the area in search of a mate.
From ID photos and tagging, the same sharks are known to visit the area year after year while pregnant.
Bull sharks have a long gestation period of around 11 months, and deliver one to three live pups.
Female bulls don’t reach sexual maturity until the age of 18, whereas for males the age is 13-15. We don’t know how long bull sharks live, but it is believed to be more than 30 years.

AFTER A FEW MINUTES of looking around, our backs towards each other, a distinctive shape headed straight for us. It was disconcerting how close the shark seemed to be compared to the supposed visibility of 25-30m, so well camouflaged was it. Once she realised that we had spotted her, she turned aside and described a lazy, curious circle round us, never coming closer than 15m before disappearing again into the blue.
We waited several minutes for the shark to reappear, then Gustavo signalled for us to follow him close to the seabed. He had told us not to swim too far off the bottom if sharks were in sight, because that could agitate them.
We were to kneel on the bottom immediately if we saw a shark, and keep eye-contact with it at all times. Bull sharks are ambush predators and known for seemingly unprovoked attacks. They have among the highest levels of testosterone of all sharks, making them prone to extreme aggression and particularly efficient at ambushing and killing prey.
The females, while pregnant and just after giving birth, produce little or no testosterone, so in theory are not aggressive. They also suppress their natural urge to eat – to avoid cannibalising their new-born pups – and consume only just enough to survive. However, bull sharks remain unpredictable, so we were to take no chances. What is certain is that they are very bold and curious.
Gustavo signalled to us to kneel as the shark approached again, still keeping her distance but circling us for some time. Again she disappeared, and we swam slightly deeper, to 19m.
The sharks are known to inhabit the entire coastline at depths from 15m to around 50m, but are mostly found between 20 and 25m.
Going deeper we saw the same shark again, recognised from a slight scratch on her side, but this time joined by a smaller shark. They maintained their distance, swimming in and out of sight.
Very soon our air was depleted – though thanks to the free nitrox tanks our no-deco time hadn’t been reached – and we started to ascend, awed by this natural sighting.

THERE HAS BEEN A GREAT DEAL of controversy about bull-shark dives in Mexico. Three or four dive companies run shark-feed dives very close to this area in around 25m depth, 500m from the beach. Some people have expressed concern that the sharks are being fed too close to areas where unsuspecting swimmers and snorkellers play, and feel an attack is just waiting to happen.
I spoke to Luis Lombord Cifuentes, the director of the local non-government, non-profit organisation Saving our Sharks.
SoS runs a scientific research project to help protect sharks in the area through tagging, air monitoring, genetic mapping, photo ID and education.
It has worked hard to get every dive-centre in this part of Mexico involved in the project. The centres are expected to follow a set standard for both shark- feeds and observational dives, and to educate their guests by providing adequate briefings and teaching them about bull sharks.
With the help of some of the leading local centres SoS designed a standard-setting manual several years ago. Pro Dive was instrumental in helping to design this manual and continues to support SoS by regularly taking its researchers out on its boats to help with their data-collection. Each supporting dive-shop charges a set US $5 fee per diver, which goes to fund SoS research.
Bull sharks are a species known to habitually live and hunt in shallow waters, Luis told me. He doesn’t think the shark-feeds unnaturally attract bull sharks to the shallows of the Yucatan peninsula.
Old fishermen tell of how they and their ancestors would catch bull sharks in very shallow water in these areas. While cleaning their catch of fish they would throw back the unwanted parts, which would attract the sharks.
This practice was, and sometimes still is, prevalent in fishing communities worldwide. The shark-feeds, according to Luis, provide less shark-food than fishermen used to throw overboard.
In more than 30 years there have been no reports of attacks by bull sharks in the area, leading to the conclusion that neither the feeds nor observational dives, which have been running for more than 15 years, are changing the sharks’ behaviour materially by making them want to seek food near humans.

AS ON SHARK-FEEDS in many parts of the world, a chum-bucket is taken down by a chain-mail-suited feeder to entice the sharks. They are encouraged to “behave“, lining up in an orderly way before approaching the feeder calmly to take a fish-head.
It may be that this food is just enough to help the pregnant females survive without needing to hunt for more, or perhaps these morsels are just canapes to the sharks, which will hunt for the small amount of food they need in deeper waters.
Research indicates that the sharks are not fed enough to keep them in the area – if they were, they would stay year-round and males would be attracted too.
However, there is a big problem with the sharks being in the shallow waters of the Yucatan peninsula. The area is not protected so fishing is allowed, and the sharks are being caught regularly by local fishermen. SoS has campaigned to stop this, and for any sharks caught to be returned unharmed to the ocean, but there are still one or two who actively fish for bull sharks.
One in particular regularly posts photographs of himself with his catches on social media.
By getting the dive-centres to participate in the shark-dives and charge their customers the SoS $5 research fee, the charity has been able to persuade the government to impose a protected no-catch area for sharks. It is hoped that this will be implemented by the middle of the year, before the next group of female sharks arrives in the area.
Fishing might bring in large taxable revenues for government, but SoS has demonstrated that by running interactive dives with the bull-sharks more money is being brought in through tourist divers.
By educating the diving and fishing community (all dive-centres have to go through an in-depth SoS training programme before being allowed to conduct shark-dives), the plan is make visiting divers and sports fishermen more aware of the need to protect sharks and help with shark-conservation programmes.
Pro Dive itself runs a five-day Shark School each year with SoS, including shark-dives with and lectures by shark behavioural scientist Dr Erich Ritter.
I have done many shark-feed dives around the world, but the observational dive was quite different. We weren’t feeding the sharks, although they were in an area near to where shark-feeds are conducted. It felt like a very natural experience for me – we were entering the sharks’ realm and they were checking us out from a distance as many other sharks would naturally do, for no reason other than curiosity.

WE DECIDED TO DO ANOTHER observational dive the following afternoon. The wind had dropped and the waves lapped the shore gently from a virtually flat sea. We dropped into fantastic 40m-plus visibility and found the bottom at 20m.
There was a slight current, which we hadn’t felt the day before.
Almost immediately a large female bull approached, coming much nearer than on the previous day’s dive. There were 14 of us. My buddy Mateusz, Gustavo and I stayed slightly separate, 30m from the rest of the group.
The shark swam a lazy figure of eight between the two groups, and was very quickly joined by another from the opposite direction.
Within minutes three more arrived and were swimming all around us, disappearing before approaching again from various directions.
As the sharks grew bolder, coming ever closer, the two groups of divers moved nearer each other to try to stop them coming between us. One especially bold shark swam directly towards us.
I didn’t think she was going to stop, so held my camera out in front of me.
She turned just as she reached my camera, skimming past extremely close. She swam on and circled behind towards Mateusz, who was a few metres behind me and around 10m from the other group. He was looking in the other direction at another shark approaching him.
The shark brushed past him and turned quickly to speed through the gap between the  divers. With the slight current, Mateusz got pushed slightly off balance, but quickly righted himself as the other shark came in close.
The dive-guides’ eyes seemed to be on stalks as they signalled for us to close the gap. Gustavo looked at me and winked, a big grin on his face – he was excited!
For the whole 42 minutes of the dive the five sharks swarmed around us. Their body positions did not show aggression – their backs weren’t arched or their pectoral fins lowered, the normal position when hunting or attacking – so I think they were just curious and bold.
In fact, as the reunited group swam away from the sharks to shallower water before ascending, one bull followed and continued to circle below us as we did our safety stop – an exhilarating experience, to say the least!
Once back on the boat, it was clear that this had been no normal dive. The dive-guides were high-fiving each other and their divers. Everyone was commenting on how close the sharks had got to me, Mateusz and the Pro Dive videographer. The dive had made my heart beat a little faster, but I had not really felt threatened.
The observational dives are made in the morning, which did make me wonder whether this dive was unusual because of the calmer waters, the slight current, or the fact that it took place in the afternoon.
The dive companies in the area have agreed that shark-feed dives should be conducted at 11am and 3pm and the observational dives at 9am and 1pm.
Our dive fell between the two shark-feeds, so fish-oils and particulates from the morning were still in the water, and as the sharks expect feeds in the afternoon, perhaps they were gathering in anticipation of it.
I don’t know, but certainly there was some reason why the sharks had acted differently to the previous morning.
We decided to do another observational dive next morning for comparison. Again, it was fairly windy, so the water was slightly choppy and visibility a little lower.

WE HAD A VERY SIMILAR experience to the first one. We dropped to the bottom at 18m and had to swim around slowly for almost 10 minutes before we spotted a shark. This time, with less visibility, we separated from the rest of the group.
The shark was beautiful, heavily pregnant and swimming gracefully towards us. Keeping her distance at first, she checked us out before moving away.
Several minutes later, just as we were about to swim again, she reappeared and came much closer. Again, she stayed for a few minutes before swimming away.
We waited, then rose from the bottom slightly to fin gently over the sandy bottom. Ten minutes later, I had given up hope of seeing a shark again. There is little to see other than sand at this site – hardly any other fish or reef.
Then suddenly the shark appeared again. We recognised her from the free-swimming remora in pursuit and the enlarged belly. This time she came much, much closer.
The remora, perhaps fancying a rest, skipped over to Gustavo and tried to attach to his tank while he was stationary on the bottom.
The shark swam round us for several minutes, very close at times though again it seemed to be out of curiosity.
As my air was almost at 50 bar, I was thankful when she disappeared again. Although I hadn’t felt threatened, being in a small group of three I hadn’t fancied ascending while she was right by us, and doing a safety-stop above her head!
I really hope that the government implements the ban on fishing soon. These bull sharks are magnificent creatures and they deserve to be protected, especially when they are vulnerable in pregnancy.

FACTFILE
GETTING THERE: BA has direct flights to Cancun, or you can fly via major US gateway cities with several airlines.
DIVING & ACCOMMODATION: You can do the bull-sharks dives from any location on the Yucatan peninsula. Pro Dive has nine centres conducting the observational dives, www.prodiveinternational.com
WHEN TO GO: Bull shark season is December-March. The females leave the area for a week or two at the end of January to early February to give birth.
CURRENCY: Mexican peso
PRICES: A bull-shark observational dive and one local dive costs US$79.
TOURIST INFORMATION: www.visitmexico.com, Saving our Sharks: www.savingoursharks.org, donations: www.prodivemex/saving-sharks