I don't think decompression sickness is the main concern here. Dive boats would usually anchor somewhere relatively shallow. You're probably making some decisio

I don't think decompression sickness is the main concern here. Dive boats would usually anchor somewhere relatively shallow. You're probably making some decision reasonably quickly so you haven't absorbed that much nitrogen yet. If you're >50m deep you have other problems (like depth narcosis). Decompression sickness can kill you quickly if you get large bubbles in your brain or heart but that's less typical. Many cases of decompression sickness can be treated in a compression chamber within some reasonable amount of time after surfacing. Onset of decompression sickness is also often delayed by as much as 48 hours.