I've been achievement-hunting lately, and just recently, after obtaining Frost Walker II, I tried to attempt the Let It Go! achievement by walking over a warm ocean. The game, unfortunately, did not say that I had obtained the aforementioned achievement. 

The achievement specifically said that I must walk over a DEEP ocean with frost walked boots to get it. So I'm assuming that when Mojang updated Minecraft Bedrock Edition to Phase One of the Update Aquatic, they forgot to update the achievement as well. So since I'm pretty sure that the old Deep Ocean biome was removed from the game in 1.4, this makes the achievement practically impossible to get. 

So fix it, so I can get my sweet, practically useless, 20G