I'm not quite 70 and was dismayed to run into the age 70 diving in the Similans out of Khao Lak, Thailand a few months back. My wife (over 70) went along on 1 boat as a snorkeler and I had to discuss with them that she was in good health and had recently been snorkeling in Hawaii, but they let her on. This does make me wonder if people who have run into this might want to start creating a database here with information such as:
Location
Dive Operator
Age limitation? (No or list age)
Details - e.g., ok if have medical clearance letter from MD, DAN or other dive insurance, hard cutoff, just needs discussion, sign special waiver, etc.