Hidden Island 8 shares Coral Cave's design. The island is a cyan grotto filled with crystalline coral forming purple surfaces, white paths, intertwining crystal- and coral bridges, and pristine pillars. The bottom of the grotto is partially flooded. Embedded in the ground are colorful gems that constantly twinkle from the light columns penetrating the ceiling. Decorating the surfaces are various colorful coral clusters and crystals. Other features include clean waterfalls and abandoned mining equipment, like pulleys, minecarts and mineshafts with lit torches.
Like most other Hidden Islands, Hidden Island 8 is a short stage which can be finished in less than a minute. The majority of this stage uses the minecart gimmick from Coral Cave Act 2, where the player rides a minecart through different sections, but is more strict in terms of platforming. Regular gimmicks include Bungee Ropes and Springs. The stage also contains no enemies.
First follow the path until the characters reach a minecart section. The following path has both an upper and lover path, so the player can let themselves fall in holes in the upper path without risks. However, the lower path's holes will be bottomless pits. After the minecart section, follow the path to another one. Ride it and evade any holes in the path until the characters enter the 3D section. Jump over or turn away from any iron balls and lava pits, and the characters will exit the minecart section and reach the Treasure Chest.