The Bulb Zone Caves are a special cave system of the Bulb Zone. It is characterized by its deeper, volcanic portions with multiple small lava rifts on its walls, along with small glowing plants found in them.
Touching the lava rifts will deplete the player's health rapidly, so avoiding them is advised.
Temperature near the vents in the fourth cave is around 60 - 70 degrees Celsius, which means the Thermal Plant can be used here, and a Reinforced Dive Suit is required to explore without taking damage. The Eyeye, Rockgrubs and Shuttlebugs inhabit these caves.
There are currently four Bulb Zone Caves known to exist:
- The first one can be accessed through two entrances, one of which is located in the Bulb Zone and the other entrance in Mushroom Forest, as the Bulb Zone Caves connect to a large cave there, which is characterized by flora typical to the Mushroom Forest. This cave is known to be the only of the Bulb Zone Caves to have a Lava Geyser in the middle of the cave and a single Brain Coral close to the transition to the Mushroom Forest Caves.
- The second cave is located under Wreck 3 and it's the second smallest cave and does lead to a Cuddlefish egg.
- A third cave can be found under a Giant Bulb Bush in the outskirts of the Bulb Zone. This one lacks the volcanic portion the others have and is the smallest of the three.
- The fourth cave is quite extensive and can be accessed through one entrance, which is located under the third cave's entrance, next to the two Sea Crowns found in the Bulb Zone. This cave is known for its many Earthen Coral Tubes, Spotted Dockleaves and Spiked Horn Grass. A single Eye Stalk can be found here as well along with a single Brain Coral.
- The Bulb Zone Caves was once known as the Koosh Zone Caves. This name was changed due to prevent potential copyright infringements.