The children from Kirkwall Grammar School were rescued by a 4×4 in a dramatic operation.
Coastguards said it was not clear if the bus had got stuck because of the weather or suffered mechanical failure.
The 33 children, plus driver, were safely transferred to a Land Rover and taken to a harbour authority building at Scapa.
All were safe and well.
The incident happened around 11.20am at Scapa Beach Road in Kirkwall.
Former Kirkwall Lifeboat coxswain Geoff Gardens, who came across the bus, said: “In all my years, this is the worst weather I have seen for many a day. The children were very lucky.”
Mr Gardens, 65, now a coxswain of a harbour pilot boat, said: “The children were all fine, but the bus was rocking. The waves were breaking over the wall – they were big.
“It took quite a few runs to get all the kids off – they were calm throughout. “It was quite a bad place to break down, but I don’t know if the bus stalled in the weather or by it.
“The road was very flooded there. It was some rescue.”
All schools in Orkney were closed from 11.30am.
Source : EXPRESS