I’m pretty sure the puppy would not have drowned (golden retrievers are very good swimmers), but still, it’s amazing.
 

The deepest swimming pool in the world was opened in 2004 in Brussels, Belgium. In fact, it's a Recreational Diving Center, called Nemo 33. The swimming pool floor consists of flat platforms at different levels. The pool has two large flat-bottomed areas at depth levels of 5m (16 ft) and 10m (32 ft), and a large circular pit of 33m (108 ft). It also contains several underwater caves at the 10m depth level. The Center was designed by Belgian diving expert John Beernaerts as a facility for instruction, recreation and film production.