Unless I “leave transform”, diving goggles do not get removed from my character. I can run anywhere in the world wearing swim trunks. Map travel does not reset it. This started very recently for me – earlier today diving goggles timed out properly.
edit:
The issue started after doing the dive at Brigatine isles. My dive count did not increase after doing that dive. I went to the Vigil keep dive next, in my swimming trunks, and put on the goggles at that site and got credit for it. After that dive I was still in swimming gear. After re-doing the Brigatine dive the goggles timed out properly and I got credit for the dive.