fishing at the river

1. I went fishing in the river. It can mean either a. or b. depending on context: a. to catch fish from a boat on the river. b. to catch fish by diving into the water. 2. I went fishing on the river. It means to catch fish from a boat on the river. 3. I went fishing by the river. It means to catch fish by dropping a line from the riverside ... film masha and the bear