Mahabalipuram, Arjuna's Penance

Famous rock sculpture in Mahabalipuram (Mamallapuram), from the Pallava Kingdom culture, ca. 400 - 730 AD. As so often there's several conflicting stories as to its meaning and no one really seems to know for sure. A common explanation is that it depicts in mythical terms the River Ganges as it flows from high in the Himalayas, but I've heard several others. Arjuna is said to be seen doing penance for Shiva, hence the name.