I doubt you can find a travel health insurance that gets more praise than DAN's. Aside from all the things we expect, like paying the bills, they effectively have a concierge service for divers. It includes some of the most complete hyperbaric treatment and diver injury expertise in the world. Simply having the ability to convince (teach) non-hyperbaric and underwater injury medical professionals to accept their input is invaluable.
In most (all?) cases they pay the medical bills and ask questions later so you are not held hostage in a foreign country. DAN probably knows more about arranging international medi-vac services for hyperbaric injuries than anyone. Granted, they may go after your primary insurer for partial or total reimbursement of their expenditures after you are taken care of, but not you. I NEVER thought I would speak favorably of an insurance company, but I am happy to pay DAN.