Liquids and seas: water, lava and stranger seas.

Water on the home planet

The home planet is mostly water at sea level, and its seas, lakes and rivers are all water. Water is the only sea you will find at home. It floats you, lets you swim, and lets you breathe under the surface only with a dive tank (see Going deep). Water flows: a hole dug next to a lake lets it run in, and a lake fills back up to its level. Spring water pours out where it comes from a cliff top, down its face into a pool at the bottom.

Lava

Lava lies deep underground, in caves below about 320 blocks, and it runs out when you open it. It burns anything not made to take the heat. Lava that touches water turns straight to obsidian. Lava that lands on dry ground makes a small pool that stays molten for a minute or two, then cools into basalt.

Strange seas on other worlds

These seas are found only in other universes. Each one is a liquid that replaces the water of a world. Some are fine to swim in, some hurt, and some heal. The temperature column shows the range of the world's average warmth in which the sea appears.

Sea	Looks like	How it treats a swimmer	Warm enough for (C)
Milk-white ammonia	A pale, milky sea	Burns you slowly, at a steady rate. Swimming is a little slower than water.	-90 to 25
Methane sea	Pale blue, cold and clear	Freezes you slowly. Nearly as easy to swim as water.	-190 to -60
Crude oil sea	Black and thick	Slows you a great deal and drags hard at every stroke. Its shores are tar sand.	-10 to 140
Acid sea	Green and bright	Caustic. Wear an Acid Suit before you go in.	15 to 150
Liquid metal sea	Silver, heavy and still	Poisons you, and floats you up out of the depths. Hard to swim in.	-30 to 200
Glowing slime sea	Bright green and glowing	Heals you slowly as you swim. Hard going, and needs a living world.	5 to 60
Living jelly sea	Pink and wobbling	Floats you up and bounces you back from falls. Needs a living world.	0 to 50
Liquid crystal sea	Clear blue crystal	Swims like water, and chimes when you touch it.	-120 to 60
Liquid sky	Deep blue, like the sky itself	You can breathe it, and you swim a little faster than in water.	-150 to 120

The sea's surface moves with the wind. Thick seas such as oil and mercury lie nearly flat. A sea that is lighter than you floats you, while a sea that is heavier lets you sink as you would in water.

Which worlds have which seas

A world gets a strange sea only in a harder universe. The more unusual the universe, the more often its wet worlds have one, and the stranger the sea. Some seas need a living world. Lava seas stay on volcanic worlds, because there the fire is the world. A dry world has no seas at all.

Oil

Crude oil also lies underground, in lenses 20 to 38 blocks under the sea bed off the coasts and under the deserts and mesas. Drill down to it, then put a pump over the bore to bring it up to the surface. Oil is also a fuel.

Tips

• Check the sea before you dive. The colour and the name tell you what it does.
• Acid and mercury will hurt you. Plan your suit before you swim.
• Water and lava both change the blocks beside them. See Digging and mining.
• For the giant sea creature of the home planet, see The Kraken, and for fish and shore life, see Animals and fishing.

← Back to the wiki · Last updated 25 October 2026. Mantlenaut is in alpha, so things change.