“Towards the end of my dive, I slowly began to sense that something wasn’t right. I’d been underwater for about 45 minutes and had less than half a tank of air. During our briefing we had agreed to ascend along the anchor line, and I knew from the depth I was at that we should have been able to see our boat. However, there was no boat in sight, and no anchor line. Our guide first ascended by himself, came back down and immediately told us to come up. By that point it had become obvious that our dive boat was no longer attached and had drifted away.”

This happened during a dive in April off Okinoerabu in Kagoshima prefecture. The actual location was a point named Oyabiccha, known for a series of boulders that stick out for miles and are an extension of the Okinoerabu mainland. While we were in the water, our boat had come loose from its mooring and disappeared.

Back at the surface, we were able to swim to shore for about 15 – 20 minutes. Landing on the rocks with all our gear was awkward, but everyone in the party managed it. From there we were able to wait for our dive guide who went back to port, returned with his van and drove us to the dive shop. Meanwhile the unoccupied boat had been found adrift a short distance away and was retrieved about two hours later.

On this occasion we were lucky; nobody was lost or hurt, there was no current or high waves and the boat was undamaged. Unfortunately this is not always the outcome for those diving from private or unmanned boats. It’s still unclear why our boat broke its anchorage, but there are a number of possibilities. A change in wind or current could have pulled it in a different direction, or the anchor line could have been cut as a result of careless placement.

Diving from a private boat must involve the skills of captain and dive master, with one person on board being responsible for the boat and the other deciding where to dive and the type of dive that will be done. The most important rule of diving from a private boat is to always leave a responsible person or people on board when divers are in the water. That person should be able to operate the boat, use the radio and respond to emergencies. A dive boat should never be left unattended.

Despite these basic rules however, it appears that unmanned boats are surprisingly common in Japan, particularly in the remote islands of Kagoshima Prefecture and Okinawa. Dive shops in these regions tend to be run by families or are short-staffed so boats are often left unmanned as a way of reducing costs. Some shops in areas that only attract a small number of divers cannot afford to hire a boat captain (who is often a local fisherman on such remote islands).

PADI Japan is aware of this fact and the risk of unmanned boats drifting away but if it’s not possible to hire anyone extra, a boat should be equipped with at least two anchors, additional ropes and anything else that will help secure it. If you discover that your boat is unmanned and you are not sure about it, you can choose not to dive. In Japan divers seldom do this. Instead they simply follow the guide, and often, during a dive briefing for example, they are so caught up in hearing about the dive site and what they might see, that the boat is the last thing on their minds. But if you are unsure about anything, whether it’s the boat or something else, you can cancel your dive.

If you decide to go ahead and your boat is unmanned, it’s also important to understand that no matter how calm the conditions are when you enter the water, it is always possible that you could become separated from your boat. Visual and audible signalling devices are crucial because the key to getting rescued is to be as visible as possible. One of the best tools to use is the surface marker buoy or SMB, the bigger the better, with a highly visible colour. Sounds from horns and whistles have a greater range than the human voice and can be quite effective, while strobes and lights, with an LED light source, will shine for a good while.

*The school where this incident occurred is called Sea Dream (http://seadream.ti-da.net/) based on Okinoerabu Island in Kagoshima Prefecture. What happened was a simple mistake: there is no suggestion that Sea Dream is habitually careless or less competent than dozens of other small dive schools in remote parts of Japan. But mistakes of this kind should not be ignored. As divers know, they can have tragic consequences.