Liquids are substances that players can swim in (that normally take oxygen from them) in Flood Escape 2. This is the main theme of the Flood Escape series.
Water
Water is the simplest form of liquid in all of Flood Escape 2. It drains your O2 meter at 8 O2 per second, which gives you around 12 seconds before you drown. There are some maps where you must swim through water like Crystal Caverns and Abandoned Facility.
Acid
Acid is the second most deadly form of liquid, and can be found in three different types or textures, usually green. When submerged in acid, a red ⚠️ sign will appear next to your air. Acid drains ~30 O2 per second, giving you around 3 seconds before you drown. In the map Poisonous Valley, the acid is a purple-pinkish liquid while in the others Relic Valley and Dark Sci-Forest, the acid is purple.
Lava
Lava is the most deadly form of liquid and can also be found in four different types. When the lava reaches a player's head, they die instantly (even with an Air Bubble). However, in Chill Mode, you can swim in lava for a short time. In most maps the lava is either a red marbled liquid, or a magma textured liquid. In the map Graveyard Cliffside though, the lava wall has a decal of ghosts, similar to the poison wall in Poisonous Valley. In the map Sedimentary Temple, a substance referred to as 'hot sand' acts as lava.
Trivia
Lagging players sometimes do not die in lava for up to a few minutes.
If you have survived a map, lava will drain your air at 75 O2 per second, which is the same speed as lava in Chill Mode.
When a liquid is changing a state, and if a player jumps into it, it still reads as the liquid form it once was which may kill players. It is recommended to wait a bit. This is not a problem in any current map but was a problem in the old Cave System.
Air Bubbles can prolong the amount of time you take swimming under water and acid.
On August 29, 2017, Crazyblox posted a tweet[1] of him experimenting with a discontinued water type, were you wouldn't be able to swim inside of it, but rather jump high, and walk almost normally. This water type and the map were never talked about again and were never added to FE2.
"NoSwim" is a fan given name for this liquid.
Acid used to be called "Toxic Water" as shown in an old screenshot [2] and video[3] of Abandoned Facility.
