A sinkhole up to 100m long and 50m deep has opened up on a south-east Queensland beach.

The hole appeared at Inskip Point, Rainbow Beach, on Saturday night and continued to grow yesterday. It is estimated to be up to 50m deep.

The sinkhole at Rainbow Beach.

Hervey Bay man Ron Morgan told the Fraser Coast Chronicle he could only watch in shock as a small hole turned into a gaping chasm 30 metres wide and kept on growing.

“The beach is just falling, it's disappearing into a giant hole,” he told the Chronicle yesterday.