The Pearl Gate, also known as Mandarin Ducks Playing in Water, is located at the southern end of Zhonghu Lake. At an elevation of 365 meters, it consists of two islands, large and small, spaced about 20 meters apart. During the dry season, the beach is exposed, connecting the two islands by land; in the wet season, the area between them becomes navigable. At the front of the smaller island stands a white marble stele inscribed with the words "Pearl Gate." Viewed from afar, the two islands resemble two "pearls" resting in the lake—glistening and translucent, radiating brilliance—or like two grand gates, towering and majestic, solemn yet magnificent, hence the name Pearl Gate. The islands face each other, shaped like mandarin ducks resting on the water's surface. When a breeze stirs, ripples form on the lake, evoking the image of two ducks playfully frolicking in the water, thus earning the alternate name Mandarin Ducks Playing in Water.

The emerald forests and wild grasses on Pearl Gate Island resemble the green feathers of mandarin ducks, as described in a poem: "Two pearls fall upon the mirror-like surface, colorful gates stand opposite each other under the sky. Shuttling boats pass through the gates, while woodcutters' songs and fishermen's chants echo over the green mountains." According to research by the Heilongjiang Provincial Cultural Heritage Bureau, as early as the Neolithic Age, the Sushen people had already thrived here. The remains of their semi-subterranean dwellings are still clearly visible today.