Erica Reef, also known as Enola Reef, Boji Jiao (Chinese: 簸箕礁) in China, Terumbu Siput in Malaysia, đá Én Ca in Vietnam, and Gabriela Silang in the Philippines, is located in the SW of Dangerous Ground, 24km east-northeast of Mariveles Reef in the Spratly Islands.[1]

It is small, almost circular, with an outside radius about 1 km. It dries entirely at low tide, enclosing a shallow lagoon. A few rocks remain visible on the east side at high water but there is no obvious point of reference. The lagoon is too shallow to be of much interest and the outer reef is a steep slope rather than a drop-off, but it descends into very deep water. Healthy stony corals harbouring a myriad of reef creatures descend into the depths and many shoals of semi-pelagic fish are seen in the clear visibility. On each reef the south walls are precipitous while their other boundaries are slopes, the walls are a result of prevailing currents and the direction of maximum sunlight encouraging coral growth.[citation needed]

The Royal Malaysian Navy has maintained an "offshore naval station" there called "Station Sierra" since 1999.[2] The reef is also claimed by the PRC and Vietnam.