Ko Chang (Chang Island) is the most notable geographic feature in the district. Ko Chang by itself occupies 212.947 km2. The district of which it is part occupies some 419 km2.
Confusion has arisen over the size of Ko Chang and whether it is the second (after Phuket) or third (after Phuket and Ko Samui) largest island in Thailand. The confusion likely arises from Ko Chang's inclusion in the Ko Chang District (419 km2) and as the largest island of the Mu Ko Chang National Park (650 km2).
Ko Chang means 'Elephant Island' and derives from its elephant-shaped headland. Despite the presence of elephants on the island, they are not indigenous. At present, there are eight villages on the island.
Prior to World War II, Ko Chang was little known. During this period, the few families there made a living growing coconuts and fruits.
On 17 January 1941, Ko Chang was the scene of the Battle of Ko Chang between the Royal Thai Navy and a Vichy French naval squadron, in which the French won a decisive victory. Ko Chang Yutthanawi Day, which occurs in late–January at the Ko Chang Yutthanawi Memorial on Laem Ngop, commemorates the Royal Thai Navy's engagement against the French. There is an exhibition by the Royal Thai Navy, and merit-making and tribute rites are performed.