If two objects are made of the same material, one large and one small, and they are submerged in water, which object experiences the larger buoyant force?

Mars has a surface gravity that is only 0.38 (a little over one-third) that of earth's. thus, the weight of an object will also be 0.38 times that of earth. what is the g.p.e. of a climber who weighs 675 newtons on earth at the top of 26,000-meter olympus mons?