From the Super Mario Wiki, the Mario encyclopedia
Bubbler's Course is the third boss course in the Nintendo 64 game Diddy Kong Racing and its remake Diddy Kong Racing DS. This course is located on Bubbler's race location in Sherbet Island. This place appears to be a water-based, circular course which features a tunnel section. The racer would need to avoid many obstacles in this course such as mines, bubbles and logs. During the first race, Bubbler drops mines to prevent the Player from winning and during the second race, Bubbler will summon bubbles.
In Diddy Kong Racing DS, the spinning logs appear to be absent from the course.