The drive unit includes a watertight elongated housing extending along a longitudinal axis and defining an inner chamber, two juxtaposed tracks disposed around the housing along its longitudinal axis and enabling the drive unit to move when the tracks are rotatably driven around the housing, and at least one track-driving motor. The motor is located within the inner chamber of the housing and includes an output shaft mechanically connected to the corresponding track. The unit can also include a ventilation circuit for the interior of the inner chamber of the housing, and a generator for producing electricity. The drive unit can be manufactured from a single housing or with the housings of two apparatuses that are juxtaposed and rigidly paired.