Trincomalee Harbour, also known as Trincomalee Bay, is one of the largest natural harbors in the world and is located on the northeast coast of Sri Lanka, in the Trincomalee District. It is strategically situated along one of the busiest maritime routes in the Indian Ocean, making it historically significant and commercially valuable. The harbor consists of a large, deep-water bay protected by natural formations, including headlands and offshore islands. The natural depth of the harbor allows it to accommodate large vessels, including cargo ships, oil tankers, and naval vessels. This has made Trincomalee Harbour an important maritime hub for trade, shipping, and naval operations throughout history. Trincomalee Harbour has played a significant role in the maritime history of Sri Lanka, serving as a key port for various civilizations and maritime powers, including the ancient Sri Lankan kingdoms, European colonial powers, and modern navies. The harbor has witnessed numerous historical events, including naval battles and strategic military operations, due to its strategic importance in controlling maritime trade routes in the Indian Ocean.

Today, Trincomalee Harbour remains an important port for commercial shipping and naval activities. The harbor is home to Sri Lanka's Eastern Naval Command, which plays a crucial role in safeguarding the country's maritime interests and ensuring maritime security in the region. In addition to its strategic and commercial importance, Trincomalee Harbour is also a popular tourist destination, offering scenic views, water sports, and opportunities for recreational activities such as boating, fishing, and dolphin watching. The harbor's tranquil waters and picturesque surroundings attract visitors from around the world, providing a unique glimpse into Sri Lanka's maritime heritage and natural beauty.