I read a small boy’s novel in 1950’s about a boy travelling to see his father on a Cessna? (or other small plane) which crashes in a Canadian lake. He befriends an otter (from memory) which catches fish for him, has some adventures and eventually escapes the situation. I have forgotten most of the details but think that he dove down into plane to recover things and had a run-in with a bear. Best thing I can recall is the front cover drawing of the young boy sitting on the lakeside with the otter beside him.
It is definitely not “Hatchet” by Paulsen which appears to be a very similar plot published much later in 1987. I have not read this book but assume it is not a reprint of the original book I am recalling.
