Bloodstained: Ritual of the Night comes with a healthy dose of good old metroidvania action. Staying true to the genre, you'll find yourself blocked from exploring certain areas until you've found a certain item or gained a new ability. It's very much the case with swimming and the Aqua Stream Shard.
Here's everything you need to know about Bloodstained: Ritual of the Night swimming and how to get the Aqua Stream Shard.
Bloodstained: Ritual of the Night Swimming
Before you can hope to have a shot at unlocking swimming in Bloodstained: Ritual of the Night, you'll need to get yourself the blood steal ability which allows you to drain the blood fountain.
In order to get your hands on the Aqua Stream Shard, you'll have to explore the lower portion of the Forbidden Underground Waterway. There, you'll find a demon enemy resembling a jellyfish which, when killed, has a chance to drop the shard.
That does mean that you might have to kill the enemy a number of times before it drops the Aqua Stream Shard. Once the item is yours, you're finally able to go swimming and explore the underwater areas in Bloodstained: Ritual of the Night.