From Sonic Retro
Volcanic Tunnel is the second level in Tails Adventure for the Sega Game Gear, coming after Poloy Forest and before Polly Mountain 1. Though thanks to the non-linear nature of Tails Adventure, Tails must return to the region on various occasions as new items (specifically, the Triple Bomb) open up new routes.
After the firestorm of Poloy Forest, things don't get any cooler for Tails as he heads underground through the scorching fissures of Volcanic Tunnel. Amidst the green rocks this stage sports lava pits and jumping fireballs in the same vein as Marble Zone and Under Ground Zone. There's a whole host of really tiny tunnels winding about the level as well, requiring judicious use of the Remote Robot and Remote Bombs.
Apart from the boss at the very end, there are actually no Battle Kukkus down here at all; presumably the birds aren't such fans of being deep underground. However, the level is abuzz with their remote robots; little white Nezu mouse-bots that scuttle around dropping micro bombs, and swooping bats that swat Tails down whenever the fox tries to take to the air.
Items to pick up in Volcanic Tunnel include: