This street market, located on the street named after the Tin Hau Temple, is a special one because it stays open long into the night. There are many shops that you can visit (selling a huge variety of different things - e.g. clothes, toys, souvenirs etc.).
There are also many places where you can get takeaway food and various Korean snacks so you can have your dinner while walking down the busy market street and hunting for some bargains.
It is not just a shopping area though. You may also come across some street artist there. The place is usually very busy (mainly after dusk when the market really starts) but it is also very interesting to visit because of its special atmosphere.
The market is most lively after 7 pm and closes around midnight.
Wikipedia https://en.wikipedia.org/wiki/Temple_Street,_Hong_Kong
Address 2J Saigon Street, Yau Ma Tei, Hong Kong SAR China
Coordinates 22°18'26.329" N 114°10'12.67" E