Yoshi's Island (race course)

Yoshi's Island is the fourth and final course of the Fruit Cup in the Booster Course Pass for Mario Kart 8 Deluxe. It is a course that takes place on the island it is named after, with its music theme being an arrangement of the athletic theme from Super Mario World 2: Yoshi's Island. It is the second course to be introduced to the Mario Kart series in the Booster Course Pass, after Sky-High Sundae. Unlike Sky-High Sundae, this course was not announced for Mario Kart Tour alongside its reveal, even though internal data points to it being developed as a new course for Mario Kart Tour.

Akin to other courses based on games outside of the Mario series, this course uses the logo for the series it is based on for its starting line, and the course itself is heavily inspired by the game it is based on, featuring obstacles like Stilt Guys and Huffin Puffins, and mechanics like Winged Clouds that can summon stretches of road when driven into. The layout of the course appears to reference all the world themes from Super Mario World 2: Yoshi's Island. Many cameos from the game appear in the background, including Incoming Chomps, Petal Guys, Goonies, an enormous Nep-Enut, and Yoshi's ally Poochy. Koopa Paratroopas and Sidesteppers also appear on the course. A near the starting line plays the same sound effect as the Paddle Platforms in Super Mario World 2: Yoshi's Island. Additionally, there is a Goal Ring near the finish line.

Similarly to Hyrule Circuit, Animal Crossing, and Urchin Underpass, this course has unique coins—in this case, the coins have the same design and collection sound effect as in the Yoshi's Island series. It also has a unique race fanfare, victory theme, and results theme based on the "Game Start", "Goal", and "Score" themes, respectively. While some other courses feature unique fanfares and results music, this is the only course in the Mario Kart series to feature its own unique victory theme. The icon for this course resembles the title screen for Super Mario World 2: Yoshi's Island.

Excluding courses announced simultaneously, this course and Piranha Plant Cove mark the shortest period of time between the announcement of two new courses for the Mario Kart series, with them being announced five days apart from each other.

Course layout
Racers begin at Yoshi's House in a field that resembles World 1 from Super Mario World 2: Yoshi's Island. Racers race along a slight serpentine path, avoiding Stilt Guys before diving into an underwater section. Surrounding the underwater section is a forest that resemble the basis' World 2 and World 3. This section ends with racers driving into a castle. Leaving the castle, racers emerge from the water and drive through a small cave. Exiting the cave, racers drive up an active volcano, like the one in World 6. A glider ramp then takes players up to the clouds, driving above snow-capped mountains similar to World 5, before taking another glider to the ground level where they can drive into a Winged Cloud to make a red bridge appear. After reaching the ground (or the aforementioned bridge), they make a right hand turn to return to the finish line.

In Time Trial ghost replays, the bridge does not appear when driving into the Winged Cloud, including both staff ghosts' replays. However, its collision is still present. The reason for this is likely connected to the same reason why coins do not disappear during Time Trial ghost replays, as they are not collected by a physical character.