Flash floods have devastated a southern Philippines region unaccustomed to serious storms, killing at least 450 people while they slept.

The United Nations has chosen Monday to mark the globe’s seven-billionth birth symbolically, sparking a string of festivities worldwide.

Cocooned in rural seclusion, Donsol, a placid little town, long kept a big but unintended secret: In the first half of the year, the sea swarms with the world’s largest fish.…