RichA writes:
Is there an advantage to taking a hulking DSLR underwater versus a smaller mirrorless camera?

Depends on which product you’re comparing (and when .. what year). For example, I bought my
dSLR housing system in 2010, I was unable to find any 4/3rds or mirrorless products (land camera
& housing) that was able to incorporate a housed equivalent (which means lens & dome port) to the
famous Nikon Nikkor 15mm wide angle (_still_ the benchmark for CFWA).

Ballast?

If you go too small, it’s lack of mass is a legitimate proble, especially for shake on video. But they
are very “ballasty” when packed for airline transport carry-on ... I’m hoping that by now things have
improved such that I’ll be able to find a smaller-than dSLR housed system for my next UW rig.

FWIW, I’d like to stay with a housing like the Ikelite I have now, as I’ve found that their design makes
it straightforward for me to rebuild it on my own, as part of the trade-off with the old Nikons was that
some of its O-rings were not user-serviceable, whichmeant sending it out for annual service, which
in the last few years was running nearly $200 per service.

-hh