In Returnal you will come across underwater items in small pools of water. But jumping into the water will hurt you. To reach underwater items you need the swimming / diving ability which you get automatically at the end of the 5th biome “Fractured Wastes”.
Here’s what an underwater item looks like:
How to get Swimming / Diving Ability in Returnal:
- Play through the 5th biome “Fractured Wastes”. At the end of this biome you will get the ability called “Hadal Ballasts” to swim/dive for underwater items. It’s an automatic story-related unlock, cannot be missed. But it’s quite late into the game.
- Simply jump into any pool of water to walk on the ground. Then jump out of it when you’re done. No need to activate the ability, it’s passive and automatically activates when you enter water.