A Late-night Town in the Bottom of the Sea

Suneo tells everyone in the Empty Lot that his cousin is very good at diving. Doraemon runs away suddenly. Nobita feels strange and follows him. When he gets home, Doraemon says that it is foreseeable to pick up Suneo. Diving in Guam and Saipan is enviable.

Nobita really says that he wants to dive. Doraemon takes out several gadgets infobox his pocket such as "Fictitious Water Simulator Pump", "Fictitious Water Experience Glasses" and "Hammer Foot Fins" (you can swim without drowning if you wear them). And starts to draw water in the room with the pump, Nobita puts on the glasses and is startled and says that the room is full of water, but he takes off the glasses and finds that it is fake water that he can't normally see.

Doraemon and Nobita use Take-copter goes to the tree in the Empty Lot to put "Spherical Fish Bait" and puts "Imaginary Seawater Gas" in the real sea (you can feel the fake water when you touch it) to attract real fish.

At night, Doraemon calls Nobita to get up, and asks Shizuka to go diving together, puts on the "Fictitious Water Experience Glasses" and finds that the whole city is flooded, and sees many fish running to Empty Lot, as well as a coconut, driftwood and others and a stray cat wants to catch a small fish, but it fails to sense the water, so Nobita begins to take pictures with the fish at the bottom of the water.

When Gian is sleeping and snoring at home, his big mouth turns into a playground for small fish to come and go. A taxi driver sees a school of fish on the street and is scared to stop. A certain dog feels alert when he sees a small fish but is scared to hide when he sees a whale. Dad sees a jellyfish shining on the street lamp, but he doesn't see it when he runs to show it to the police. The police thinks he is too drunk and thinks he was a Martian. After the police leaves, Dad sees another jellyfish and thinks it was a Martian to touch it, scared by tentacle stings and run away. After Nobita and Doraemon meet the examinee first, they send Shizuka home first.

On their way home, they see the examinee running and shouting. A snapper is swimming around her, and when Dad runs home, he sees Mom picking up the net and catching fish. The examinee tells the police what he is watching, but the police feels that he is overworked and mentally disturbed, and advises him to go back to sleep.

When Nobita and Doraemon are looking for a shark, they find a fin at the corner and approach them. It turns out to be a dolphin. They think that the examinee sees the dolphin as a shark. In the end, the two ride the dolphin to help it return to the sea.

After playing, they go home and turn off the machine, and the two fall asleep together. The next day, He is feeding the fish in the pond in the yard, and it turns out that shark comes out of the pond!