The Durmstrang ship is strangely skeletal to look at, as though it is a resurrected wreck, with dim, misty lights shimmering at its portholes. The ship is used to transport the Durmstrang Headmaster and students.
From the Story
Discovered in Book 4, Chapter 15, Beauxbatons and Durmstrang, Moment 2 The Ship
"The Durmstrang students use the ship to travel to Hogwarts for the Triwizard Tournament. It appears to travel below the surface of water, appearing only when it is ready to moor. A great disturbance takes place in the lake when the ship begins to ascend; great bubbles form on the surface of the lake, and a whirlpool appears in the centre, as if a giant plug has been pulled from the lake floor. The ship rises slowly from the water, the mast appearing first, and glides towards the shore once it has been fully revealed."