For simplicity, I specified that the faster land animal would run 30 mph for the whole 100 meters. I think that's probably pretty generous for any kind of bear, but I know those guys are surprisingly fast, so I figured that I'd err on the fast side. The main point of my illustration, however, was to show that a relatively small advantage in swimming speed can make up fo a much greater disadvantage in running speed, because much more of the time for the top contenders will be in the water.
I'd be surprised if a cheetah can swim fast enough to catch the otter by the finish line. Even if he can average 4.0 mph in the water, an otter that swims 7.0 mph can jog through the 100 meters on land at 12 mph (5-minute mile pace) and hit the tape before the cheetah is out of the water.