Westreme Battery is a former artillery battery located in Mellieħa. It was built by the Order of St. John in 1715-1716 as part of a series of coastal fortifications around the Maltese islands.

Much of the battery has been destroyed over time, but the blockhouse still exists. Today it is open to the public as the Tunnara Museum, which is a museum dedicated to tuna fishing.

This battery was probably named after a knight of the same name, and was one of two batteries that guarded Mellieħa Bay, the other being the Fedeau Battery, which was destroyed. The area was also defended by the Mellieħa Redoubt in the center of the bay, but this no longer exists.

The layout of the Westreme Battery was similar to that of the nearby Mistra Battery, but on a larger scale. The battery also had a single blockhouse. It was in fact one of the largest blockhouses of all the coastal batteries in Malta. These characteristics made the battery unique, unlike any other battery in the Maltese islands.

In 1748, the tunnara was inaugurated by Grand Master Pinto at the Westreme Battery. The military importance of the battery diminished over the years, and it was used as a storehouse for fishing nets and other equipment used in the tunnara.

During World War II, the blockhouse was converted into a beach station. Machine gun portholes were cut into the building. Another concrete beach post and a searchlight site were also built near the blockhouse. After the war, the blockhouse was used again in the tunnara.

The semi-circular firing platform and the parapet of the battery no longer exist, although parts of the rock-cut base are still visible. Today, the blockhouse is still intact, and is open to the public. Its exhibits focus on traditional Maltese tuna fishing.