Despite other explosions not breaking blocks when underwater, fireballs and wither skulls can still destroy blocks even when submerged.

How to reproduce

1. Create an underwater space.
2. Place some blocks on the center of the space.
3. Summon a fireball.
4. Punch the fireball into the blocks of the center.

Expected result
The fireball would have exploded without destroying the blocks in the center.

Observed result
The fireball destroyed the submerged blocks on impact, despite the explosion going underwater.