As a fan of recycling and green technology, I found it an interesting challenge to design drones that would help clean bodies of water. While there already are solutions in real life that collect garbage from the surface, I thought that not all trash floats, some of it sinks and stays submerged on the bottom. If it's toxic or dangerous to animals (like ghost nets), it could be a problem. I was looking at references of technology that could help the drones be as silent as possible (not to disturb wildlife) and batteries that don't use heavy metals, in case the drone itself sinks. Picking up trash and delivering it to the main ship to earn points could also be an additional gameplay mechanic in a video game.