Not really long exposure tho, as you can do this without a tripod (or simular)
Nope... That's where the high ISO comes in. These new-fangled cameras are awfully good with "noise"
I am going to try to light up the entire bow of an old schooner in Tobermory one of these days. The challenge is coordinating a half-dozen competent divers in 110' of water at night. With my friends, any dive scheduled after happy-hour is likely to be cancelled. I might need to bribe them! ;-)