whilst we were in gwldln a dwarf told me a story of such a pack of fish that together pushed a ship right up onto a large flat iceberg where it was beached for forty days , the fish kept returning and grabbed men from the ice if they had ventured from the ship to try and get it back into the water or for other reasons , he said it was almost like the fish had pushed the ship there to be some kind of convenient larder of food for them .