Beaver Bros.

The Beaver Brothers swim around in the Waterfall Rapids at the source of the river in Majora's Mask. Mikau tried to race them in order to obtain an empty bottle from them, but ultimately failed. Thus, when Link first meets them in his Zora form, they mistake him for the guitarist of The Indigo-Go's.

In order to obtain a bottle, Link will have to race the two brothers separately. These creatures consider empty bottles to be very valuable items and won't give them up so easily. First, the younger brother will challenge Link, and if the young hero succeeds, the beaver will call his older brother to race against Link. This time, Zora Link will have to go through even more rings in order to win against the big brother, and upon completion, the two beavers will forcefully reward Link with an empty bottle.

Link can race again to win a Piece of Heart from them, for they seem to have run out of empty bottles. This time, the time limit is shortened for both races, and if Link succeeds, the Beaver Brothers will hand over a Piece of Heart in hopes that he'll finally leave them alone.

In none of these races does Link actually have to beat the beavers. He merely has to keep up, get the rings, and cross the finish line within the allotted amount of time.