 John followed his father, Frederick, into naval service, joining his father’s ship unofficially, at just ten years old.At fifteen he enlisted with Nathaniel Portlock on a commercial expedition to what is now Alaska and the Canadian Pacific coast (then a bare and savage coast), where he learned the principles of seamanship in difficult climates and the handling of small ships, which was very advantageous to him, given that he spent most of his career in such craft.After a period of service as a midshipman in the Royal Navy, Lapenotière again took a leave of absence, to accompany Portlock and William Bligh on a breadfruit expedition to the South Pacific, to replace those plants lost following the Mutiny on the Bounty.