Answer
At the same level.
Work Step by Step
We know that the new planet has a larger acceleration due to gravity. This implies that one's body weight will be increased. However, it is also true that the weight of the displaced water (consider Archimedes' principle) will be increased by the same factor (since they both depend on $g_{planet}$). Thus, a person will float at the same level on the other planet as on the Earth.
