belly flop

Translations
прыжок на живот
He attempted a dive but ended up doing a belly flop.
Он попытался нырнуть, но в итоге сделал прыжок на живот.
Definitions
A belly flop is a type of dive into water where the diver lands flat on their stomach, causing a loud slap against the water's surface, often resulting in discomfort or embarrassment.