The Update 1.4.0: Update Aquatic - Phase One Title update for Minecraft (Android) has 8 achievements worth 200 gamerscore.
Visit all ocean biomes
Eat nothing but dried kelp for three in-game days
Collect a fish in a bucket
Spend a day underwater.
Find an underwater ruin
Power a furnace with a dried kelp block
Dig up a buried treasure
Find a shipwreck