Here's an article on how I've been
Packing Photo Gear.
This is personal preference, of course. I carry all the cameras, lenses, lights, 2 strobes in a discrete backpack that rarely gets weighted. Note that this backpack is heavy and many folks will opt not to have a heavy backpack. My carry on-roller, which gets weighted every flight to Asia, contains just my housing with a camera body in it and smaller ports. If hassled for being 10-11 kilos instead of 7, I just show them it's camera gear. At worst I remove the camera body, put it on the counter, reweigh the bag and get the Ok, then put it right back in the bag as soon as I walk away from the counter.
I use a padded bag with chargers, extra batteries (*this can be a risk), extra strobes and lights, etc in one of my two checked bags.
If traveling to a destination with a lot of carrying the rig around, I'll throw a cooler bag into my dive bag to use on site (just like a number of divers mentioned above). It's awesome. For most of my diving out of the car here in California I also keep the rig in the cooler bag, and somethings bring the extra port, batteries, etc in a padded case inside a peli box that keeps it safe camping and all that.
So so many ways to approach packing! The key considerations are 1) your gear, 2) what airlines you use (e.g. how strict they are on carry on weight) and 3) the type of dive op you'll be using (e.g. how you'll move gear around onsite).