Final answer:
The Irish Sea separates Great Britain from Ireland to the west.
Step-by-step explanation:
The sea that separates Great Britain from Ireland to the west is called the Irish Sea. This body of water is a significant geographic feature of the British Isles, acting as a natural boundary between the two islands. It's an essential route for maritime traffic and has historically been important for trade and travel.
The Emerald Isle and the Western Highlands are just a few splendid geographical features that add to the diverse landscape of the British Isles.