We had exactly the opposite experience. We flew to the Big Island on December 28 and stayed in Kona.
Testing at the airport before the trip was a snap, and although we were also given an antigen test on arrival, it went very smoothly. During our stay, the Covid positive test rate on the Big Island was about 1.5%, apparently 0% from howlie's
Except for a Manta dive, and a pelagic night dive, I'd rate the diving as a big "meh". Although I've never dived in Maui, I have dived on Oahu, Kaua'i and now Hawai'i. I guess it is what experiences you're coming from. If local diving is a quarry,
then Hawai'i (the state) will paradise. If your experiences are the Caribbean or SE Asia, at least you're getting wet, but the fish variety and colors are very subdued.