The Shell's Secret

The Shell's Secret is the sixth episode of Noki Bay in Super Mario Sunshine. The episode's objective is to climb up to a large shell and clear its secret course.

Layout
To access the secret course, Mario has to climb up the large pillars in the center of Noki Bay and use the tightropes between them to jump higher. Several of the tightropes have Wire Traps moving along them, with the blue ones simply moving along the rope and red ones that will follow Mario. Alternatively, the player can climb up the mountainside and jump to the spiral platform across, then take the tightropes to progress. Once Mario enters the purple shell, Shadow Mario will appear to take F.L.U.D.D. away and Mario will be brought to the secret course.

The Shell's Secret is made up of several spinning and moving platforms. The player will begin in a glass box that Mario has to Wall Jump out of, followed by jumping across a spinning then a rotating platforms. The next set of platforms will slide in and out of the wall, but the ends of them will not in all the way. Afterward, the player needs to climb a pole then use a tightrope to jump onto an above platform. Mario then has to use Side Somersaults and Wall Jumps to climb up to the next segment, which is made up of long, rotating blocks and a stack of spinning platforms Mario has to use the Side Somersault to climb up. At the end of the third rotating log is the Shine Sprite.

Red Coins on the Half Shell
Returning to this secret course will allow Mario to use F.L.U.D.D. and do a Red Coin challenge. After the first set of moving platforms is a Red Coin Switch and Ground Pounding it will cause eight Red Coins to appear throughout the course. The player needs to collect them all within a time limit of one minute and thirty seconds to earn a Shine Sprite, otherwise Mario will lose a life. The locations of the Red Coins are:
 * On the wall next to the switch.
 * Over one of the sliding platforms.
 * Next to the slope with arrows.
 * On the end of the wall over the slope.
 * On the wall with the window.
 * Over the following set of platforms.
 * Just before the first rotating log.
 * After the first rotating log.