etak is a word of Micronesian origin for a distinctive cognitive and mnemonic approach to oceanic navigation and orientation involving a notional reference point or "island", called etak, and triangulation based on it.
The system under that name was found in the Caroline Islands, and the literal meaning of etak is "refuge".
This phenomenon leads to the use of a relative frame, in which the boat is considered to be at rest, while the etak moves.
Equivalently, the etak is the common point of a pencil of lines, based at the vertex of a triangle opposite the route of the boat.
The practical techniques used by the navigators of ocean-going canoes were researched by Thomas Gladwin and David Lewis, and published in the early 1970s.