Starting Tunnel

The Starting Tunnel refers to the first part of stage 1 of Versus Mode and Co-Op. It also appears in later stages of those game modes (after stage 9) due to a random stage exclusive to those game modes being picked after stage 9.

Technical analysis
Starting Tunnel is the start segment of the first stage (segments/split/split_start/start.xml.gz.mp3 and segments/split/split_start/start.mesh.mp3).