Years ago I walked the Lamma Family Trail, an easy, fully paved trail of about 5k across Lamma Island near Hong Kong. It's generally well trafficked but I only saw a few people that day.

It was hot and the path isn't shaded for the most part, and by halfway through I'd finished my water. I started to get a little concerned, but I'd passed the point of no return so continued. Anticlimactically, I made it to the other end, found some water and chided myself for worrying unnecessarily.

A couple of years later, I met a woman whose son had collapsed from dehydration on that same trail. He fell into some foliage, and wasn't found for several hours. He survived but apparently it was close.

Really easy to underestimate risk in those situations. That poor family.