Without light, there is no photography. You need to add strobes to your system to bring out the reds, oranges, yellows, and purples that would otherwise fade away underwater.
Fitting your Nauticam housing with an Ikelite bulkhead is easier than ever, and it's a sure fire way to get the right exposure using true TTL connection.
Adding a second strobe is great for wider and more even coverage. Learn about how to connect one and other considerations when shooting dual strobes underwater.