Any underwater drones small enough to fit in aquarium?

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PowerVision Powerray Explorer Underwater Drone for Exploration, Diving, and Boating - High Definition Camera, Equipped with 4K Ultra HD Video Camera, Remote Control, and Live Stream Capability : Electronics

Ukraine sea drones outsmarting Russia's superior navy - Asia Times

Critically endangered North Atlantic right whale found dead off Georgia's coast - Whale & Dolphin Conservation USA

VIDEO: Houthis Capture U.S. Navy Drone Off Yemen

GLADIUS MINI dives deep! Meet the world’s first 5-thruster mini-size underwater drone with intelligent control algorithms. View real-time 1080P video,

Chasing Gladius Mini-size Underwater Drone with 100ft Tether

Webinar – The Future Of Underwater Drones

8 Best Underwater Drones for Sale [2021] - With Camera

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What are some technologies used in submarines and/or deep water exploration vehicles? - Quora