I never get nausea on the surface except just after a dive. On my last dive I vomited under water. I never get motion sickness either on board a boat or flying an airplane. I am an 8000 hour pilot and have done aerobatics and regularly fly in very turbulent air with no nausea problem. The only thing that seems to help is to have zero for breakfast.
All dives are before lunch.
However, the nausea started well before the heartburn. About 4 years ago I started experiencing severe nausea during diving to depths of 50 feet. I never get nausea on the surface except just after a dive. On my last dive I vomited under water. I never get motion sickness either on board a boat or flying an airplane.