"Secret Course" (also known as "A Secret Course") is a frequently ripped track on the SiIvaGunner channel.
"Secret Course" is the track used for the bonus levels in its game of origin, Super Mario Sunshine. It is an arrangement of "Ground Theme" from Super Mario Bros., which became common for bonus area music in later Mario games.
This particular arrangement is unique among its contemporaries as it is an a cappella arrangement, or in other words, its instrumentation comprises only vocals and finger snaps (though it is not a real a cappella recording; the track is sequenced).
An extremely similar arrangement known as "Trampoline Time" also exists. It is played in a few minigames in Super Mario 64 DS and New Super Mario Bros.. This arrangement is nearly identical to "A Secret Course" until the 35-second mark.
Although "A Secret Course - Super Mario Sunshine" was the first rip of this track on the original GiIvaSunner channel, there existed a melodyswap of this song by toonlink before the GiIvaSunner channel was created; this remix has been cited by Chaze the Chat as one of his inspirations for creating the channel. On the channel's first anniversary, it was remade as "A Secret Course (Anniversary Edition) - Super Mario Sunshine".
In December 2020, following GilvaSunner's September 2020 updates to his channel's Super Mario Sunshine playlist, every extant rip of the track was renamed from "A Secret Course" to "Secret Course".