In Norse mythology, Skidbladnir is the name of the boat that Loki gave to the Aesir to win back their favor after he had cut of Sif's hair.
This boat was made by the dwarves who lived in Svartheim, along with the spear Gungnir and an enchanted spun-gold wig that began to grow when it was placed on Sif's head.
Skidbladnir had the incredible ability to sail on any sea, but it could be folded up so small that it could fit in someone's pocket.