The Arbor

The Arbor is an island off the south-western coast of Westeros, separated from the mainland by the Redwyne Straits. It is part of the Reach and its rulers, House Redwyne, hold fealty to House Tyrell of Highgarden. House Redwyne controls a large fleet from the Arbor. The Arbor is famous across much of the known world for its high-quality wines.

Season 1
The poisoned wine a wineseller in Vaes Dothrak uses to try to kill Daenerys Targaryen is said to have originated from the Arbor.

In the books
In the Song of Ice and Fire novels, the Arbor is the biggest shipyard in southern Westeros. Its fleet is one of the largest in the realm, behind only the King's Fleet and the Iron Fleet of the Iron Islands. Locations on the Arbor include Starfish Harbor and Vintown.