I upvoted you because you are pointing to a logical explanation for an "accident". For those out on paranoia, let's consider the circumstances:  The object of the boat tour was diving. So 34 people standing in line to do 2 dives a day, that is at least 68 bottles to fill. How do you fill a bottle?  First off you need a fill station, usually a compressor driven system. Second, there are some technical issues to respect when doing this. Usually, nothing goes wrong, even when a mistake is made. It is quite a safe thing.  Personally, I own a tank set designed by Jacques Cousteau from the sixties. I have it checked every year, and it is doing nicely. But then again not everybody is as careful with equipment as I am, not the least, stumbling happens. I mean, you simply have a bad hair day, you forget to check you O-rings, tubes, stages, and whatnot for wear and tear and one day you bumb into something. Whatever. So, the technical state of a bottle or bottle set is important. Corrosion, crevices of the tank itself, state of the nozzle, etc. So, here's what happens when filling a tank. And multiply that by 68. If you do this daily, everywhere people work, a mistake is made. Some fill stations use water to cool the tanks, because they get hot when being filled, but cool later on and the pressure drops somewhat with 5 -10%. When filled while cooling, the actual PSI may be reached.  Here's what happens when you make de mistake to fill-up a tank above and beyond it's tolerance limit. The question then is: was the fill station an automatic system or not. If not, who was guarding it's operation?  Additionally, perhaps there are nitrox divers. There are several ways to provide this and make this.. This means, there are additional tanks with gasses to mix. For a million $ self designed and built boat geared towards diving, I would not be surprised if the boat was equipped with it's own nitrox fill station.  So, basically, there are a host of maintenance issues that need to be taken into account. Human error is possible on all stages. Then, we are talking about an installation on a marine environment, especially a salt marine environment. This requires additional safety and maintenance levels.  Lastly, for this item, some tanks have a wrapping and may not be that fire prevention friendly.    It goes to show, how many instances there are for human error, but it also lends for situations that can be sabotaged. You would need to have a good reason to suppose sabotage.  Even having an innocuous lighted sigaret may cause big problems. I know of many divers who like a sigaret after diving.  Fires on a boat can happen. There are either of three components that need to be absent to kill the fire: Oxygen, flammable material, temperature of ignition.  One of the causes, depending on the type of engines used, may be a lack of ventilation enriched by patrol vapor. Not ventilating first and starting an engine/ compressor/ generator or even light switch, may cause a fire/ explosion.  Depending on how meals are being cooked, gas installations in a marine environment need regular inspection to make sure, connection, rubbers, etc remain in safe condition.  Not every fire can be fought with the same material. A sprinkler may use water, but may not be the best solution.  Some people say: there should have been a deck watch .... well, if an explosion takes place, a deck watch is of no good, as you already are in deep doodoo. check the boat layout. But an explosion does not mean high temp. It simply blows the compartment where it happens opens up. If the fuel containers are ruptured or punctured by flying debris, then a fire with high temp may ensue, causing the safety valves of the compressed gas bottles to blow. In such a case, I would expect a more severe situation.  Then there is a difference between Diesel and Patrol. Just the fact that the boat has a capacity for fuel, does not mean shit. The question is: what fuel is on board, and where is it located, in what kind of containers? You might be thinking, Patrol ignites way easier than Diesel, because of the flashpoint of patrol is very low. If the right circumstances are met, Diesel ignites just as easy. e.g. droplet spraying diesel ignites causing a roaring fire.  An instant extreme rise in temp, may cause gas bottles to blow. This also means certain parts of the tank will act as a claymore mine, exacerbating the situation.  https://www.yachtingmonthly.com/archive/how-batteries-can-explode-and-how-to-avoid-it-3930 This article explains what happens to batteries and overworking them. When you look at each stage of the supply chain, it is easy to see how things can go wrong. Even on sophisticated boats like the Russian sub that caught fire around Kola a few months back, the real danger of fire caused by electric malfunction is very real. The Germans designed a sub Type 212A based on fuel cell technology. You should really check it out. It speaks to safety precautions.  And since the vessel Conception is made of wood, chock full of flammable material ....And the applicable safety standards are not in the same league as with subs .... so you do the math.  Before starting out on paranoia, and discount an accident, which, given the relative rare occurrence of boot fires, there are quite a number of things to consider first. What did actually happen before the boot was a raging inferno, capable of acting like a cremation oven. So what is the likely scenario? That still remains to be seen, especially, given the fact that a boat is just a small space, filled with potentially dangerous material. And a human error can cause a cascade of serious issues, causing the inferno. Shit happens.