[Experimental] Boulders in the Mega/Giant Taiga biome can generate underwater

When you're exploring around the mega/giant taiga biome, you notice that some of the boulders generate underwater.

Step to Reproduce
1. Find a mega/giant taiga biome.
2. Go find a river, ocean, or aquifer generating within the biome.

Expected Result
No boulders generating underwater.

Observed Result
Boulders generate underwater.