Islands may be detectable from 100+ miles away, based on how they affect wave, wildlife, and cloud patterns. Rapa Nui is 2000 mi from Chile, but "only" 1000 mi

Islands may be detectable from 100+ miles away, based on how they affect wave, wildlife, and cloud patterns. Rapa Nui is 2000 mi from Chile, but "only" 1000 mi from Pitcairn islands, which were occupied by Polynesians in ~1000AD. Also, consider how many expeditions probably went out into the Pacific and everyone died there. Calories are relatively easy to harvest in many polynesian islands, leading cultures to send excess people on expeditions to discover and colonize new islands.