(with pics)

A quiet morning's diving turned into a struggle for survival when a dayboat caught fire off Belize recently. BSAC advanced instructor Stephen Mowvley reconstructs the drama with the help of other divers who were there on the day

It was a seemingly perfect day of blue skies and flat seas, and we had just dived the Blue Hole and Half Moon Caye, two of the most popular sites in Belize. Our dive boat operator had made fulsome dive and safety briefings, so my friends and I were truly relaxed, not suspecting that in the following few minutes we would be abandoning our boat in a situation that might have left us all dead.

I wanted to tell this story so that other divers can realise how quickly an extremely dangerous situation can blow up when at sea. Certainly, there was little time to spare when our boat caught fire and exploded.

So, here is my timetable of events, with approximate times estimated amongst myself and the other divers who shared this terrifying experience.

1.10pm: After lunch, with our cameras full of underwater photographs and video footage, we return to the boat in high spirits, ready for the final dive of the day on the famous Aquarium dive site.

1.20pm: We pull away from the jetty and the dive guides brief us on the third and final dive of the day at The Aquarium. We settle down for the short trip to The Aquarium. Some of the divers on board start to kit up, while others sit and wait.

1.25pm: A crew member reports that oil pressure on one of the two diesel engines has suddenly dropped. A few seconds later there is a loud, metallic bang from below deck in the engine compartment and a few trails of grey smoke start to rise from the hatch. The crew immediately shuts down both engines and we drop anchor as soon as possible.

1.26pm: The smoke starts to billow out in great volumes, making it difficult to breathe inside the semi-enclosed boat; we are told to move to the bow to avoid the smoke. The crew is still trying to determine the extent of the blaze at this point, but it soon becomes clear that the engine compartment is ablaze and out of control; opening the hatch, with the sudden intake of fresh air, would create an inferno.

1.28pm: The smoke thickens into a black toxic cloud, making breathing all but impossible. Flames suddenly burst out of the engine access hatchway and it is now evident that there is no safe way to contain the fire.

1.30pm: Several of us, crew included, move back to the stern down the walkways on the outside of the boat, calling to others to get off the boat and start to try to unload jackets and cylinders (which were all ready for the next dive) into the water as flotation aids. However, the fire is now so intense that it is impossible to reach all the kit.

Divers move to the platform, grabbing personal items on the way before jumping off the back of the boat. One of the crew disappears into the smoke and returns with armfuls of life preservers (how on earth he managed to do this is beyond me), which he throws them into the water for those with no means of floatation. The senior guide takes a final look around to make sure everyone is off the boat, lifts a final BC and cylinder into the water and dives into the sea.

1.33pm: Only minutes have passed since the initial puff of smoke, but the boat is now seriously ablaze. Efforts to swim clear of the boat are hampered by surface wind and current. Disoriented couples are shouting to each other across the water, anxious to confirm each other's safety.

Small local fishing boats - plus another dive boat - come as close as they dare to pick up those in the water. As we climb into a rescue boat, our kit is removed and stowed by the rescue crew, and water is handed out to wash the taste of smoke away. We are 250m from the blazing dive boat, but we can hear the sound of air and oxygen cylinders blowing their valves, the rushing gas feeding the flames.

A head count confirms all divers and crew are safe, and we are taken to a dock on Long Caye, roughly a mile from the site of the stricken boat. Boats are dispatched from San Pedro to transport everyone back to the mainland.

6pm: We are safe on dry land, ready to hit the town. Terrifying as the experience was, there's something about surviving that gives you a lust for life, so we celebrate with gusto, drinking cervezas late into the night and toasting our fortune. What did we learn? Well, fire is the number one hazard, even on board a vessel surrounded by water! The speed at which this fire took hold and spread took us all by surprise.

That said, trained divers are usually prepared and do not panic; they rely on their intuitive reactions and that meant no one lost their heads at the crucial moment. My advice is to imagine the worst-case scenarios, and be prepared for them. Even when you're on holiday, you shouldn't let your guard down.

• Photographed and compiled by Nils Iikklala, Mike Dodds and Steve Mowvley