Four specialists from the speleology team were able to access the cave on Sunday in the Cantabrian municipality of Arredondo, after 22:00 (21:00), although they only managed to advance about 50 metres due to the water level, according to EFE news agency.

The emergency service of the Cantabrian government, which is coordinating the operation, said in a statement that experts indicated that the water is dropping inside the cave at a speed of 10 centimetres per hour, much slower than originally expected.

The rescue team set up a camping site at the entrance to the three lakes area waiting for the water level to drop.

The State Weather Agency forecast is for low rainfall in the morning, with no rainfall in the afternoon, but the weather will get worse on Tuesday.

The rescue team may have to install ropes and handrails today if the water level does not drop.

The four Portuguese cavers entered through the Cueto entrance at 11:00 (10:00 in Lisbon) on Saturday according to the Spanish emergency service, quoted by EFE.

Not having heard any news from the speleologists, three other companions entered at noon (11:00 in Lisbon) on Sunday by Coventosa to see if they were there, but the high water level made it impossible for them to continue so they called the 112 which sent out the rescue team.

The operation involves the Cantabria speleology team (ESOCAN), in addition to technicians from the General Directorate of Interior of the Cantabria government, Civil Guard officers and volunteers from the Arredondo Civil Protection Association.