[3][4] MT Vector was a small motor tanker, built in Manila, Philippines in 1980 as Oil Nic-II, with a tonnage of 629 grt and a length of 51.7 m (170 ft).

Doña Paz was a passenger and cargo vessel owned and operated by Sulpicio Lines, plying the route of Manila/Tacloban/Catbalogan/Manila/Catbalogan/Tacloban/Manila.

At about 10:30 p.m. on 20 December 1987, the two vessels collided in the open sea in the vicinity of Dumali Point in Tablas Strait between Marinduque and Oriental Mindoro.

As the two vessels collided, Vector's cargo ignited and caused a fire that spilled into the water and rapidly spread to Doña Paz, which sank within hours.

Following investigations the death toll of passengers and crew from both ships was estimated to be 4,386,[2] although admitting that only 1,568 were on the manifest (still more than the licensed maximum of 1,518).

[9] The Court ruled that "MT Vector was unseaworthy at the time of the accident and that its negligence was the cause of the collision that led to the sinking of the Sulpicio vessel.