Endless Mine is an underground-themed Zone and has numerous similarities to Mystic Cave Zone and Lava Reef Zone. It features a dark cave background with purple rocks similar to the ones from Lava Reef Zone, while the Zone's rocks are green and yellow with wooden structure forming paths.
At the starting point, items from the Competition Mode are floating around the hall. When the player is bounced away by a red spring, he/she has to break through yellow colored piles of rocks by using the Spin Jump or Spin Attack in order to go down.
After that, the Zone starts overlapping and the player has to pass through a U-shaped gap and get to the right route. If the player has too much speed while running or performing the Spin Attack, he/she will fly forward through the Zone and fall down after hitting a wall, losing precious seconds in the meantime. It is therefore recommended to run through the U-shaped section at a suitable speed. The player then has to run through a shuttle loop to get back to the starting point of the Zone.
- In the console/PC version of Sonic Generations, a small piece of this Zone's music is sampled in the second verse of the Classic remix of "Escape from the City".