General Locks

Doors Locks

These require having acquired the appropriate upgrade, and you must have ammo available.

Normal Door: These can be opened with any weapon. They also open automatically if the player is launching Horizontally or Vertically.
Elemental Door: Requires the matching Elemental Weapon to leave the room.
Missile Door: Requires a Missile to leave the room.
Big Missile Door: Requires a Big Missile to leave the room.
Big Bomb Door: Requires a Big Bomb to leave the room.

Normal Gate: These can be opened with any weapon from the correct side (1-way). These can also be opened from the wrong side with the Quantum weapon.
Missile Gate: Requires a Missile to open the gate from the correct side. (1-way).
Big Missile Gate: Requires a Big Missile to open the gate from the correct side. (1-way).
Elemental Gate: Requires the matching Elemental Weapon to open the gate (1-way).

Blaster Block: Shoot it with your gun to break. Always openable as long as you can hit them.
Elemental Block: Requires the matching Elemental Weapon to break.
Bomb Block: Drop a bomb or Big Bomb while in Cat Form to break.
Missile Block: Requires a Missile or Big Missile to break.
Big Missile Block: Requires a Big Missile to break.
Big Bomb Block: Drop a Big Bomb while in Cat Form to break.
Sprint Block: Run through these at high speed to break.
Launch Block: Hit these while launching horizontally to break.
Crumble Block: Stand on these from above to break.

These require that you both have the suit and that it is enabled.

Hot Area: Requires the Heat Suit to greatly reduce damage take over time in these areas. If the Defense Suit is also equipped, no damage is done at all.
Cold Area: Requires the Cold Suit to greatly reduce damage take over time in these areas. If the Defense Suit is also equipped, no damage is done at all.
Water: Movement in water is dramatically slowed down and more difficult. Liquid Suit makes it like normal movement.
Mud: Movement in mud is near impossible. Liquid Suit makes it behave like Water.
Hot Water: Behaves like normal water with the Liquid Suit. It hurts you over time without the Heat Suit.
Cold Water: Behaves like normal water with the Liquid Suit. It hurts you over time without the Cold Suit.
Lava: Behaves like Mud with the Liquid Suit. Hurts you very quickly over time. Damage can be reduced with the Heat Suit and reduced more with the Defense Suit, but it will always hurt you.
Liquid Methane: Behaves like Mud with the Liquid Suit. Hurts you very quickly over time. Damage can be reduced with the Cold Suit and reduced more with the Defense Suit, but it will always hurt you.

High Ledge: This is a ledge that requires High Jump to reach. (150% normal jump height.)
Double High Ledge: This is a ledge that requires Double Jump to reach. (200% normal jump height.)
Triple High Ledge: This is a ledge that requires both High Jump and Double Jump to reach. (300% normal jump height.)
Vertical Shaft: Requires Vert Launch upgrade to launch yourself vertically. This uses energy to continue the vertical launch, so you must have enough available to complete it.
Dash Gap: Requires the Dash upgrade. These are completed by jumping off one side and dashing to get to the other side.
Tunnel: Cat Form is small enough to fit through tunnels.
Tunnel Gap: Requires Cat Claws to cross since wall climbing also allows pulling up onto ledges.
Wall Climb: Requires Cat Claws upgrade to climb walls. Only works on walls that are climbable.
Wide Chasm: Requires the Horizontal Launch upgrade. These are completed by launching yourself horizontally as a cat.
Wall Chasm: Requires Cat Claws and launching yourself with the Horizontal Launch upgrade off of a wall.

Killing a biome boss gets you the Orb of the opposite biome. They were guarding it to prevent it from being used against themselves.

Biome Boss Door: These are indestructible until the player has the correct Orb, then they become normal doors.
All Active Orbs Gate: These are indestructible and remain closed until the Orbs from the bosses of All Active Biomes have been acquired. Which biomes this requires depends on the world that was generated. Typically you'll find these blocking your path to the End Boss.
End Boss Door: The end boss door is indestructible until after the End Boss has been defeated, then it becomes a normal door.