I don’t know of any. The reason given is that many of the dives are deep, more or less straight down to 30 mts for the most of the available dive time. It’s enough, honestly. You see lots of marine life from the boat, huge schools of dolphins and if you are lucky mantas and we even saw a sperm whale once. The boats are all for up to 24 to 30 divers, but there can be as few as ten passengers. As I am sure you know all diving is from a dhoni, which is spacious and has a toilet on board. Dhoni diving is brilliant, reduces noise on the mothership and rendre is relaxing space. Buddy pairs and teams, maximum of 6 but usually only 4, jump in May together.
Really recommend Emperor boats !