Minecraft wiki entry for Lava, associated text: A player with Fire Resistance can swim in lava without taking damage, although the swimming speed does not become faster.
A player cannot sprint-swim on lava.
An arrow shot into flowing lava catches fire, but not if shot into still lava.
A water source block placed 1 block away upward diagonally (but not through corners) from a lava block first flows in the direction of the lava, then other directions facing away from the lava. This happens because water physics treat the lava block as empty, and try to flow to it. Once the water turns the lava into obsidian, the water physics update to flow in all directions. (The same thing happens with lava flowing over water.)
Although lava is a fluid, it is not possible to drown in lava. This applies to all mobs. However, it is still possible to suffocate in lava. This applies to almost every mob.‌[Bedrock Edition only][5]
A player sleeping in a bed cannot be damaged by lava.
If the lava is changed to be transparent via a resource pack, it does not become transparent.
Unlike water‌[Bedrock Edition only], lava does not deactivate elytra.
It has never been possible to create infinite sources of lava by regular means. Despite this, the Minecraft: Combat Handbook (2014), stated the possibility to create infinite sources of lava by simply creating a cross shape with 4 nether bricks and placing lava in the middle. As expected, this turned out to be false, as confirmed by Dinnerbone.[6]
Despite behaving identically to water while in the Nether, it is not possible to create infinite springs of lava in the Nether.