HP Up Locations

Part of the World generation includes tiles that might spawn a Extra Max Health (30% chance), a Treasure Chest (40% chance), or nothing (30% chance).

There is a video guide explanation for how to effectively utilize these:

Noita Guide To Finding Early Game Health - DunkOrSlam

Mines

Collapsed Mines

Coal Pits

	This tile can spawn with different 'puzzles', as seen below.

Fungal Caverns

Snowy Depths

	This tile can alternately spawn a slightly different pixel scene, as below:
	This tile can contain one of three pixel scenes, or can be empty, as seen here. One of the pixel scenes, the 'tiny observatory', an inverted metal capsule with protruding steel pipes, itself contains a location for a possible heart spawn. These pixel scenes can also spawn on tiles that don't have a possible heart spawn.
	Although this pixel scene contains a potential heart spawn, the tile it is loaded on top of does not. (To summarize: the 'tiny observatory' is always worth checking for its inner heart, but the buried eye and protruding pipes are only worth checking if they do not have an ice bridge to the left.)		Another tile that the 'tiny observatory' pixel scene can load on top of.

Hiisi Base

Underground Jungle

Lukki Lair

Vault

Temple of the Art

	This tile can alternately spawn a slightly different pixel scene, as below:
	This tile can alternately spawn a slightly different pixel scene, as below:

Overgrown Caverns

Wizards' Den

Power Plant

Frozen Vault