(CNN) -- Search crews in Indonesia have suspended efforts to locate two tourists, still missing two and half days after the tourist boat they were traveling in sank. The head of the rescue mission says the search will resume on Tuesday morning.
Officials say 23 other passengers and crew were rescued, pulled from the water by local fishermen and search and rescue teams. The survivors spent more than 36 hours in the water.
The two people missing are believed to be Spanish, other passengers on board said. However, officials at the Spanish foreign ministry could not confirm this.
The tourists -- mostly from Europe -- were on what was supposed to be an exotic getaway: a cruise from west to east, departing from Lombok in the province of West Nusa Tenggara and ending in Labuan Bajo, in East Nusa Tenggara, with a number of stops along the way. Under normal conditions, the journey would have taken four nights to complete.
Everything appeared fine when the vessel, named Versace Amara, set sail last Thursday. Three days into the trip, the boat ran into trouble.
Budiawan, head of the rescue mission, who like many Indonesians goes by one name, says it's believed the boat hit rocks off the volcanic island of Sangeang, at about 1 a.m. on Saturday morning. Water began leaking into the vessel, forcing the passengers and crew to abandon ship.
The vessel was carrying 20 tourists and three local crew members and two local guides.
Budiawan says authorities were first notified of the incident on Sunday morning, and immediately deployed crews to the site. The nearest town is Bima on the island of Sumbawa -- a two-hour boat ride away from where the boat sank.
The passengers appear to have split into two groups. The first, consisting of 10 tourists, remained near the accident site. They were rescued on Sunday afternoon. Five were picked up by local fishermen, the others retrieved by search and rescue teams and taken to hospital in Bima.
After being rescued, one of the passengers identified as Rafael, criticized the lack of equipment on the boat. "On the boat there was no security. No radio, no GPS, no navigation equipment. There were nothing," he told CNN affiliate Trans7 Indonesia.
"Only life jacket, but life jacket it doesn't work. If you're in the middle of the ocean with a life jacket, what happens? Nothing. Because the most important when you have an accident in the sea is to call the rescue team and to call the radio, GPS or something. They had nothing. In the morning, the crew said 'No one is coming to rescue us.'"
Another 13 passengers and crew swam in the water using lifebuoys and life vests to stay afloat. They were retrieved by local fishermen on Sunday evening, in the waters of Sape, a town in East Nusa Tenggara province, and are currently being treated at a hospital there.
Budiawan says it's believed the two missing men who were with the second group became separated because of the strong winds and current.