Jakarta. Indonesian search and rescue authorities have launched an operation to locate a boat carrying 11 foreign tourists that lost contact while crossing the Gulf of Tomini off Central Sulawesi, officials said on Saturday.

The vessel was carrying 13 people, including 11 foreign tourists and two Indonesian crew members, when it disappeared en route from Sanctum Una-Una Dive Resort to Marisa Port.

Indonesia's National Search and Rescue Agency (Basarnas) said it received a report of the missing boat at 3:40 p.m. local time on Friday from a tour guide identified as Mimin.

The boat departed the dive resort at 7:30 a.m. local time and was expected to arrive at Marisa Port at around 11:00 a.m. It had failed to reach its destination by 3:00 p.m., prompting authorities to launch a search.

"Of the 13 people on board, 11 are foreign tourists, while the remaining two are local crew members," Heriyanto, head of the Basarnas office in Gorontalo, said in a statement.

The search operation resumed on Saturday with joint rescue teams divided into three search and rescue units covering the vessel's expected route in the Gulf of Tomini.

The first unit is using the Indonesian Navy patrol vessel KAL Limboto to search an area of about 200 square nautical miles. A second team aboard Basarnas' RIB 03 inflatable rescue boat is covering approximately 50 square nautical miles along the shipping route, while a third team is deploying a speedboat provided by Sanctum Una-Una Dive Resort to search another 50 square nautical miles.

The operation involves personnel from Basarnas Gorontalo, the Marisa Search and Rescue Post, the Basarnas office in Palu, the Marine Police, the Indonesian Navy's Marisa post, KAL Limboto, and the dive resort's rescue team.

Heriyanto said rescue crews were facing difficult conditions due to strong winds and rough seas. However, weather data from Indonesia's Meteorology, Climatology and Geophysics Agency (BMKG) indicated generally fair weather, with waves of 1 to 1.5 meters (3.3 to 4.9 feet) and winds of 10 to 15 knots.

"We have deployed all available personnel and equipment together with supporting rescue agencies. We are continuously monitoring weather conditions and adjusting the search pattern as needed. We hope everyone on board can be found as soon as possible," Heriyanto said.

The nationalities of the missing foreign tourists have not yet been disclosed. Authorities have also not released details about the type of vessel involved.