| Zadetkyi | |
| Settlement Type: | Island of the Mergui Archipelago |
| Coordinates: | 9.9583°N 98.1889°W |
| Area Total Km2: | 176 |
| Elevation M: | 864 |
| Pushpin Map: | Myanmar |
| Pushpin Label Position: | left |
| Timezone1: | Myanmar Standard Time |
| Utc Offset1: | +6:30 |
| Subdivision Type: | Country |
| Subdivision Name: | Myanmar |
| Subdivision Type1: | Region |
| Subdivision Name1: | Taninthayi |
Zadetkyi Island or Zadetkyi Kyun, also known as Saint Matthew's Island, is an island at the southern end of the Mergui Archipelago, Burma. Its northern side forms the southern shore of Hastings Harbor, where there is a base of the Myanmar Navy.
Having a length of about 35km (22miles) and an area of 176km2, Zadetkyi is the largest island of the southern group of the archipelago. It has two prominent peaks, the highest of which is 864 m and is located near the middle of the island, at its southern end rises a 585abbr=on0abbr=on high summit.[1] The island is hilly and densely wooded and lies 2.5km (01.6miles) south of Hastings Island.[2]
The Alladin Islands, the largest of which is Than Kyun, are a scattered cluster of islands extending to the W and SSW of Zadetkyi Island.[2]