In the book, Ned Land is best known for what profession?

Ned Land, despite his surname, is no landlubber; he is actually a harpooner by profession. This makes him the ideal companion for Professor Aronnax and his assistant, Conseil, as they embark upon their expedition to investigate sightings of a strange, giant sea monster.
Ned is just the kind of man to have alongside you on such a perilous voyage: he is brave, strong, honest, and cool under pressure. This is just as well when you consider that our intrepid voyagers need to do battle against cannibals, giant squids, and a gargantuan sea monster that actually turns out to be an equally gargantuan submarine helmed by the twisted, egomaniacal Captain Nemo.
Ned's good old-fashioned common sense also comes in handy on the voyage. Whereas Aronnax and Conseil are somewhat overawed by the charismatic Nemo, Ned is none too impressed by the salty old sea dog. His long experience at sea makes him wary of the Captain; there is something about the man he just does not trust. This is for good reason too.