Dream Sea (夢の海 Yume no Umi) is the seventh episode of Yatterman Night. It aired on February 22, 2015.
Delirious from hunger after days without food, the gang come across a masochistic fisherman named Ryu, who they initially believe to be a turtle that would take them to the Sea God's Palace like in the legend of Urashima Tarō. Taking advantage of this, Goro sends a turtle, which the gang are too delirious to identify as a Yatter Mech, to take them to an underwater power plant disguised as the Sea God's Palace, where the Yatter Soldiers lay a trap for them. While the others are knocked out by sleeping gas, Ryu tells Galina, who snaps out of his delusion, about his dream to escape through the walls surrounding Yatter Kingdom and find his own Sea God's Palace. After waking up the others, Galina comes up with an escape plan in which the gang use an Octopus Mech as a decoy while they escape using a Squid Mech. When the Yatter Soldiers pursue them with their own Yattersunfish Mech, the gang steer it into one of the fans in the wall, allowing Ryu and his turtle friends to swim through to the other side.