It is one of the most sought after marine animals for photographers, who wouldn’t want to have a turtle as a model for a session?
Not too elusive really, perhaps often shy, it lets itself be approached and with a little patience even gives us some nice close-ups.
Much could be said about this splendid reptile from the dinosaur period… One thing that intrigues at least me who has the apnea fixation, is that hey can stay underwater normally for several minutes but also for many hours if the environmental conditions allow it (for example in cold water that slows down their metabolism) and even sleep underwater.
In my opinion, all possible lenses and types of lighting can be used. You just need to be clear in your mind about the end result you want to achieve.
Clearly, to make the best use of ambient light you need to be close to the surface.
The discussion of depth of field is interesting, since the subject often lends itself to nice close-ups, although with wide-angle lenses it is difficult to get a good blurred effect on the background to give three-dimensionality.
All diving modes can be used, in my opinion.
Normally turtles do not move too frantically, so for a short swim you can try your hand even with scuba equipment or rebreathers.