Toxic Caves, known as Toxic Pools in the 8-bit versions, is the first level of Sonic Spinball for the Mega Drive/Game Gear/Master System, leading on to Lava Powerhouse. As with other stages in this game, Sonic must bounce through the pinball-like level, acquiring Chaos Emeralds which are in turn used to access the boss. In this stage, there are three to find.
Toxic Caves is a disgusting, slimy dungeon, filled to the brim (literally) with horrible green ooze which is all kinds o' deadly. The level encompasses the half-submerged caves at the foot of Mt. Mobius, where Sonic washes up after being blasted off the Tornado during his and Tails's approach to the Veg-O-Fortress. In keeping with Eggman's general ethos regarding environmentalism, the fat man is using the caves as a dumping ground for kilotons of radioactive slurry produced by the Fortress' cruel industry. Rusted sewer pipes snake through rocks dripping with fluorescent green pollution, and the waters below are patrolled by an immense robotic sea-serpent.
A giant mechanical scorpion with Robotnik's face (and apparently his distaste for movement, too), Scorpius generally just sits at the top of the level, periodically spitting drops of green toxicity out of his stinger. To defeat him, simply leap into the gap between his body and his tail; Sonic will rattle around like... well, like a pinball, inflicting vast quantities of damage. Although if you want to make the environment do the work for you, hit the four switches above the boss to initiate a landslide of rocks that'll smash him up.
In the 8-bit versions, the boss of Toxic Pools is instead a variant of the Robo-Boiler from Lava Powerhouse.
- This is the only level in which the very bottom is not the only place where lives can be lost. The middle section of the level is dangerous for the green sludge below the flippers. However, this does not necessarily make Toxic Caves the most dangerous level in Sonic Spinball.
- After collecting all three Emeralds in this opening zone, the barrels in the middle section start to move, so they will not save the player from draining the ball (Sonic) unless lucky enough for them to be in the right place at the right time. Magma Worms stop appearing at this point.
- A glitch in this level will sometimes allow Sonic to pass through the covers that block the way to the middle section until the slime is drained from the tank in the middle, although the central Emerald cannot be collected while the slime is still there.
- The music for Toxic Caves appears as an unlockable music track in Sonic Generations.
- This is the only level renamed in the 8-bit conversion, and the only level with a significantly different layout.