On the afternoon hours of December 21, the 128 meter long, 8753 dwt container ship Kuala Mas (IMO:9555632) sank in Kupang Bay off Bolok Village, West Kupang District, Indonesia. The Kuala Mas was proceeding from Makassar to Kupang with cargo of containers loaded with rice and cement.  Reports state the Kuala Mas had suffered a breakdown and went adrift before it allided with the anchored 127 meter long, 12959 dwt tanker Maritim Khatulistiwa (IMO: 9300776).  The allision resulted in a hole in the hull below the waterline on the Kuala Mas. The vessel suffered water ingress and  developed a 10 degree list to starboard.

After several hours of attempting to control the flooding, the crew determined the water ingress could not be abated. The master of the Kuala Mas decided the only action left was to head for shallow water to prevent the vessel from sinking in deeper waters. The vessel headed towards the Bolok Kupang pier, but the Kuala Mas was in danger of sinking before reaching the dock. Authorities received a request for evacuation with the NTT Police responding. Three rescue boats arrived and transported all 20 crew safely to shore. No reports of injuries.

The Kuala Mas would later capsize and sink a short time later. Many of the cargo containers broke free from the sinking ship with some floating away while others sinking to the seabed. Authorities plan to collect the floating containers. A boom was placed around the wreckage to contain any oil pollution. The incident is under investigation. The Kuala Mas had previously caught fire back in 2018 off Nirwana Island.