Abstract: An exercise machine adapted for training watersports athletes has a pair of spaced-apart vertical columns each with hollow tubular body with a weighted plunger attached to a cable for vertical reciprocation while a user performs power and return stroke movements on an instrument attached to the other end of the cable. The plunger is hydraulically coupled to an air channel fed by an air-through valve sized to control air movement into the air channel by the rising plunger during a power stroke to approximate water resistance to an oar, paddle or arm in the water. The air channel has a release opening for releasing air balanced against the weight of the falling plunger to approximate lifting an oar, paddle, or arm out of the water on a return stroke. The exercise machine can be used to practice a wide range of watersports training exercises for swimming, paddleboarding, canoe paddling, rowing, etc.