How do you get in water areas in Castlevania symphony of the night inverted castle

To enter water you'll need the holy symbol, one of the harder objects to find. First, obtain the merman statue in the normal castle. Head back to the longest drop that leads down to the caves. Continue directly down until you find a giant crack in the floor. chop it open and ride the waves to the holy symbol. You can also make it pretty quickly with wing smash if you have life to spare.