A lifeboat (箱舟, hakobune?, lit. "ark") is a device used to travel across worlds and through time. In Kingdom Hearts Union χ, some of the Dandelions use the lifeboats to escape the collapse of Daybreak Town.
According to Darkness, the lifeboats are intended for traveling between worlds, not through time, even though they are capable of doing so. Additionally, although the lifeboats can travel to and from the data world as well as travel through time, they cannot do both at once. Using a lifeboat is the only known way to travel through time without giving up one's body. However, doing so requires the traveler to have a "medium" with which to rebuild their body as well as someone with memories of them at their destination.
The lifeboats are first mentioned by Darkness, who tells Maleficent that there is a way for her to escape from the data world and return to her own time. Darkness leads Maleficent to where the seven lifeboats are stored in the Clock Tower of Daybreak Town. Lauriam attempts to stop Maleficent, but is defeated, and one of the lifeboats is destroyed in the process. Maleficent takes one of the lifeboats from the data Daybreak Town to the real Daybreak Town, and then from the real Daybreak Town back to the future, where she appears in Kingdom Hearts II. The departure of the first lifeboat triggers the beginning of the destruction of both the data Daybreak Town and the real one.
After Maleficent's departure, Luxu uses one of the lifeboats in the real Daybreak Town to send a cloaked figure that he calls "the true Dandelion" to the future.
Later, Lauriam, Ephemer, Skuld, Brain, Ventus, and Elrena use the remaining lifeboats to escape from the data Daybreak Town. The lifeboats are able to be transferred between the real world and the virtual world, as Brain appears to send two lifeboats from the real world back to the data world for Ephemer and Skuld.
Between Kingdom Hearts Birth by Sleep and Kingdom Hearts
Hollow Bastion has a similar lifeboat device to the one in Daybreak Town. This one has five lifeboats instead of seven. During the Heartless invasion of Radiant Garden, Terra-Xehanort captures Kairi and places her in the lifeboat, explaining that he seeks the Keyblade by sending her to see if her heart will resonate with a Keyblade wielder's.
The lifeboat device from Hollow Bastion is seen again in Kairi's memory of Radiant Garden.
The lifeboats are brown, cylindrical containers large enough to contain a person. They have a single door that hinges open from the top. On the outside, they have metallic decoration and a tinted, heart-shaped window that resembles the Heartless emblem. The interior features a similar metallic decoration that resembles circuitry. Their inner workings appear to contain blue and red wires, as seen from the lifeboat that was destroyed in the clash between Lauriam and Maleficent.