Barmouth RNLI inshore lifeboat was out on exercise on Sunday 17 January when, at 10.58am, there was a launch request from the Coastguard.
A RIB had been spotted lying on a muddy bank about a mile past Penmaenpool Bridge near Llanelltyd on the River Mawddach. The RIB had broken its mooring before being washed up the river.
There were no reports of anyone on board and it was uncertain where the RIB had come from. The lifeboat arrived on the scene, and after the crew had anchored the vessel, they returned to the lifeboat station.