Hi Patricia. I am a retired commercial Diver and life support tecnician but haven’t been in the water since I’ve had this disease. There are some online diving doctors you can ask this question of. I’m sure you could easily find them with a search.
My main concern I think would be that with the increase in metabolism with hyperthyroidism that there would be an increase in the cellular inert gas uptake rate in hyperbaric conditions. In other words you could possibly be more susceptable to the “bends” (no fun, had them 4 times) so I would stay way clear of “No D” limits or possibly stick to shallow water.
Do be sure and check with a diving Physician, especially in regard to medications. Some reactions to prescription meds are affected by pressure.
Bruce