Night dives in the Sister Islands can be fun.
I don't know what type of heavy lights you have, but I carry a pair (one for backup)of small Princeton Tech 4AA lights which I pack in my carryon. They give plenty of light for night dives in the clear Cayman waters. I do see idiots who lug cave lights and blast them into the eyes of the critters (and other divers), and then complain about the night dives. With a small light, using only as much of the beam as necessary, it is possible to get up close and personal with the nighttime denizens. Many savvy photographers use only their modeling lights.