They were discovered by two British divers on a ledge in a cavern after a marathon search operation in the Tham Luang caves in Chiang Rai.
The challenge now will be to extract the party safely, with rising water and mud impeding access.
Families of the missing group were ecstatic at news of the rescue.
Rescuers had hoped they would find safety on a ledge in an underground chamber nicknamed Pattaya Beach but they were found 400m (440 yards) away having moved to higher ground to avoid the rising water.
How did they find them?