Trat is the last proper town in eastern Thailand before the Cambodian border and the island ferries. Most travellers know it only as the place to sleep before boats to Ko Chang, Ko Mak, or Ko Kood, but that is selling it a little short.
The centre is small, low-rise, and easy to like: old wooden shop-houses, a good evening market, Chinese-Thai shrines, and a slower pace than the islands offshore. Wat Buppharam is the standout historic temple, while Wat Yothanimit and the streets around the city pillar give you a compact sense of the town.
Trat also makes sense if you want to see the mainland coast before boarding a ferry. Ban Nam Chiao, southwest of town, is a working fishing and ecotourism community where Buddhist and Muslim families share the same estuary. Laem Ngop Pier is the classic ferry-side waypoint.
Do not plan Trat as a beach destination; plan it as a humane pause between long bus rides and island boats. One night is enough for most travellers, but it is a pleasant one.