COASTS File

What are COASTS files and how to open them

Are you having problems opening a COASTS file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your COASTS files.

What is a COASTS file?

A .COASTS file is an AmiAtlas Coasts Data file.

AmiAtlas Coasts Data is a geographic map data file used by AmiAtlas, a mapping application for the Amiga computer. It stores the shapes of mainland shores as filled polygons, representing land masses where the sea meets solid ground.

These files are produced and used within AmiAtlas. They are part of the geographic data directory of a map, along with other files for islands, rivers, borders etc. AmiAtlas reads them to display the coastline in maps; they are not standalone documents.

The content is structured as vector polygon data, where each polygon outlines a coastline area. These polygons are used to draw the continuous land-sea boundary in the map display.

The file begins with an ASCII header signature: at byte offset 0 it contains the string "AMIGA_ATLAS_COASTS".

How to open COASTS files

Important: Different programs may use files with the COASTS file extension for different purposes, so unless you are sure which format your COASTS file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 31, 2026

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