"and he also drank juice made from pressed fish he caught along the way." That juice is mostly water, fresh water. I don't know too much about the central the

"and he also drank juice made from pressed fish he caught along the way." That juice is mostly water, fresh water. I don't know too much about the central thesis of the book ie that you can drink small quantities of sea water and continue to thrive. However I do know that several/many/most? sea predators survive purely on the water they get from their prey. Maintaining a desalination plant is probably quite costly so eating them along with work in progress seems logical. The main idea seems reasonably sound. You need to keep the salts gradients to within parameters that your body can deal with whilst supplying it with enough water to function. It seems fair that if you start off well hydrated and only sip small amounts, regularly then your body might be able to do the job. On balance, I'd concentrate on catching fish and keeping the sea water intake to a minimum.