The 120-foot (36-meter) vessel, which furnished petroleum fuel products to other vessels, ended up with its stern on the seabed and the tip of its bow sticking up out the water.

It was carrying 750 tons of fuel oil and 260 tons of diesel for other ships, plus a smaller amount of diesel to run its own engines.

Divers have determined the ship’s tanks did not rupture, and the leakage is from the diesel used to power the engines, said Gabriel Mas, a spokesman for the port.

He said the spill had been contained by floating booms and would not reach open sea, and estimated crews had syphoned off around 1.8 tons of diesel mixed with water.

The cause of the sinking was not immediately known. No one was injured.