Sijyu

In good weather, and especially during the busy summer tourist season, there are several ferries each day to Dongjyu and Sijyu from Nangan's Fuao Port (50 min, NT$140). If you want to see both, the way to do it without having to double back to Nangan is to start with Sijyu, spend the night there, then catch one of the six daily ferries that leave on the hour, every other hour (7am-5pm; 10 min, NT$20), stopping off at Dongjyu on the way back to Nangan.

2007, Stephen Keeling, Brice Minnigh, The Rough Guide to Taiwan (Rough Guides), Penguin, →ISBN, →OCLC, page 498

This is the southernmost inhabited island in the Matsu archipelago, actually consisting of two islands, Dongjyu (Dongju) and Sijyu (Xiju).[…]Sijyu is a little more lively, but you'll likely be the major attraction, given the island’s lack of actual tourist sights.

2007, Phil Macdonald, “Straits Islands”, in National Geographic Traveler: Taiwan, 2nd edition, National Geographic Society, →ISBN, →OCLC, page 206, column 1

Departure times for Lui Guan to Nangan are each schedule times mentioned above plus 50 minutes, for instance to get on board for：The first boat of the day, Please be at the dock of the Tung Lui or Sijyu at 08:20 for the Ticketing； The last boat of the day, Please be at the dock of the Tung Lui or Sijyu at 15:20 for the Ticketing.

連江縣政府

2019 September 20, “Communication”, in Lienchiang County Government [連江縣政府], archived from the original on 31 Mar 2023, Tourism

For Matsu, Jyuguang Township (莒光) includes two major islands, Dongjyu (東莒) and Sijyu (西莒), as well as smaller islets.

2023 March 9, Ling-ling (張玲玲) Chang, “Soldiers should keep complaints off Internet”, in Taipei Times, →ISSN, →OCLC, archived from the original on 09 Mar 2023, Editorials, page 8