I haven't done a whole lot of traveling either, but one pretty tame instance does come to mind (and it's not from my Costa Rica trip a couple years ago!).
While helping conduct vulture surveys in the southern US, my supervisor (and driver) decided to go for an unplanned birding trip after finishing the route. I had never been to the Southern coast, so we hit a state park beach to look for shorebirds and more. The walk was fantastic, with hundreds of Brown Pelicans and lifer Wilson's Plover and Marbled Godwit to go along with the usual array of southern herons and ibis.
However, the shorebird roost happened to be a very tidal sand spit, which I didn't realize until I looked behind me and realized the water was coming in! I assumed it would be quite shallow and enjoyed playing Snowy Egret to wade through. Then things got a bit tricky, as we hit a spot that looked shallow but was actually waist high. We were in jeans and sneakers, so not at all prepared for a deeper water crossing. We had no choice but to forge ahead, though, as this was becoming a channel and the water was really flowing now. I went ahead, now even deeper, with scope held high in one hand and binoculars in the other. It wasn't until after we made it through that I realized the camera and my phone had been in my pockets! Not surprisingly, both were decidedly deceased. Thankfully neither was that expensive, though, turning a slightly scary situation into little more than a humorous story.