The amateur cavers, aged 25 to 55, set off on Saturday morning for a two-day guided bivouac excursion inside the Hölloch cave network near Lucerne, one of the largest caves in the world.
But the group became trapped by rising water and were unable to leave the cave as planned on Sunday, Schwyz cantonal police said in a statement.
The Muotathal branch of Speleo Secours Schweiz, the country’s cave rescue service, was mobilized and a team of four men sent to reach the group.
The rescuers reached the group after eight hours, using a different route that is much more demanding, meaning the amateur cavers cannot use it to leave, said 20 Minutes on Monday.
No one is injured, they have enough food and water for the time being, and they are able to shelter in their bivouacs above the flood waters.
However it is currently not possible to estimate when they will be able to leave.
With over 200km of chambers, Hölloch is among the ten longest caves in the world.
It was first explored in 1875, and is now a very popular place for guided caving excursions due to its fascinating rock formations and cavernous spaces.
Speaking to 20 Minutes, Franz Auf der Maur of Speleo Secours Schweiz said the qualified guide leading the trapped group has 25 years experience, and that he hadn’t necessarily done anything wrong by taking them inside.
“I would probably have also gone down into the cave in those conditions. We thought it was going to start to snow, but in fact it continued to rain, which is why the water level rose,” he said.
If, as forecast, it continues to rain on Monday it could take longer to get the group out, he said.