Marina Greenwich sits precisely at longitude 0°00'00" — the only marina in the world positioned exactly on the Prime Meridian. A marker on the dock lets you stand with one foot technically in the Eastern Hemisphere and one in the Western. It's a small piece of geography that sounds like a gimmick but becomes genuinely strange when you think about it: this quiet Spanish marina is the point from which all the world's time zones are measured.
The marina itself is well-appointed, with berths for several hundred vessels and a waterfront restaurant strip. It lies about 3 km north of Altea's old town, just off the N-332 coast road near the Meliá Altea Hills resort. Even if you're not arriving by sea, it's worth the short drive for a sundowner at the dock and a look at the meridian marker.