APPARATUS FOR IN-WATER EXERCISES, comprising; --a structure to be submerged in a body of water; an actuator mechanism movable through the user's effort; a pump comprising a housing fixed to the structure and journalling a shaft on to which at least one first rotor is mounted coupled to the shaft, at a first housing portion, said shaft being coupled to the actuator mechanism, whereby to be rotationally driven, to pump water; a water collector coupled to the first portion of the housing to receive part of the water pumped by the first rotor; and a metering means comprising at least one first display fixed onto the structure and coupled to the water collector, whereby to indicate at least on of the outflow and volume of water pumped through the pump and, thus, the respective operation speed and/or the amount of exercise being practiced.