If you have homeowner's or condominium owner's insurance, you should look into whether it covers personal property loss/damage while away from home, as many do. That's the only insurance I have for lost/damaged personal property. I don't have expensive camera equipment--like tens of thousands of dollars--but if I did, I might look into a separate rider for that.
Aside from personal property loss/damage, I would separate dive accident insurance and "travel" insurance in my mind before making decisions. They are two different things, and there is no inherent advantage to buying them from the same company. DAN's dive accident insurance seems well liked--I can't recall any instance where someone says DAN did not pay up. On the other hand, I vaguely recall a few complaints about DAN's travel insurance. Travel insurance covers things like trip cancellation and interruption and lost/delayed baggage. I have bought travel insurance for a couple of expensive liveaboard trips, but usually don't bother with travel insurance for trips on which my itinerary is more flexible, not incredibly expensive, or not paid 100% in advance.