A very ancient energy efficient method of locomotion among water dwellers is the lateral wriggle, a wave travels from the head to the tail while it increases in amplitude. Aquatic animals like eels and lampreys use this swimming motion.
The eel ship
This trade ship is composed of a puller at the front that pulls a long line of cargo units. It mimics the undulating swim technique from the eel and the lamprey. When the ship reaches a harbor it can leave the modular cargo units temporary behind. The cargo can easily be detached or reattached to the eel ship.
The detachable cargo units are frequently used to grow crops. Such cargo unit then operates as a greenhouse. The ships sails land-inward and leave their cargo behind at small harbours. Especially in dry regions the supply of fresh food comes in handy. A regular eel ship counts a crew of 15 men. The puller counts a control room, a steer chamber, a kitchen, a living room, an entertainment room and sleeping pods. The crew has access to sublime gardens that are towed along. On longer journeys, one of the greenhouses can even serve as a living space.