Baishayu is situated in the waters 4km off the north of the main island, the geological time is 13.2 million years, and it won its name due to the large patch of white sand beach (baisha means white sand) southwest of the this island. Its basalt columnar joints are well-developed. On the east side of the lava plateau is a basaltic dike which is 50m long, and a semi-circular crater-like terrain, with a bulging beach rock on the beach, part of the joints bearing chessboard-like chaps, very interesting to watch along with the pot holes scattered in between.

Jishanyu is situated 4km off the northeast of Beiliao Village in Hushi Township, this island was originally a lava plateau, but was split into two, one large one small, due to intense abrasion (but can be connected when the tide ebbs). The large Jishanyu is surrounded by an abrasion ditch and several sea caves; the small Jishanyu is surrounded by perpendicular basalt columns with clear rock joints, tall and short columns are tightly linked together, looking like a "pipe organ". It is an extremely magnificent sight. Every summer, various Family Laridae migratory birds come to this island to dwell and breed.

Dinggouyu is situated 1km southeast of Jishanyu. This island is located in a remote place where the current is rapid, tourists are rare, and cliffs are steep. The geological time is 11.8 million years, and it is formed by 4 basalt rock reefs. The entire island is composed of denser basalt, and the rocks often contain peridotite clusters; the lava flowing to the surface cooled off into different directions of columnar joints due to its different space and location, creating various peculiar shapes.

This island is located near Penghu Channel. Since the ocean current is steep, the lighthouse is set for the vessels to identify their direction. There is columnar basalt beneath the lighthouse. Near the pier, porphyrite can be seen as well. Underneath it, there is wave-cut platform which is formed by volcanic agglomerate. Inside the rocks, people can find pyroxene minerals which are the most famous source of pyroclastic rock in Dongji Island. The north and south terrain of this island is higher, which is around 47 meter high; the middle of the island is low and also the urban area.

Xiji Island is situated around 5km west of Dongji Island. It is flat basalt mesa. The columnar basalt on the west and northwest of the island is 800 meters long, which is the most spectacular view on the island. The most steep parts are mainly on the north and the highest part is about 23 meters.

It is situated around 7km south of Wangan Island. The island is composed of rocky reefs, and there are 6 big main ones. The basalt here is tilted and covers on the top of volcanic breccias, which causes surface of unconformity. Steep terrain, rocky reefs and difficpty in access make it a perfect place for many kinds of terns to rest and breed. In the volcanic breccia layer, there are three dikes in the initial analysis, and 30 to 50 meters each. Lithologic character is swarthy basalt. Several dikes run through the wave-cut platform and there are pot holes on it as well.

It is named after the shape of two huge sea stacks standing on the wave-cut platform. This island is also the resting and breeding place for terns and migratory birds.

Mao Islet is situated around 16km south of Wangan Island. The island is formed by basalt. Overlooking Penghu County Mao Islet Seabird Refuge from above, you can see two cat-shape islets on the ocean. The large islet is the highest location in Penghu archipelagoes with height of 70 m, and has a marine abrasion platform on the east side. The small islet is located on the east of the large islet, yet attracts few tourists because of its basalt formation and steep cliffs. Consequently, the small islet preserves complete natural resources, and provides terns a perfect habitat. Every summer, the uninhabited islands in Penghu will become breeding grounds for summer seabirds. The seabird resources on Mao Islet are the most abundant and special. In May 1991, Penghu County Government announced that Mao Islet was a seabird refuge in accordance with the Wildlife Conservation Act. Hence, Mao Islet became the first seabird ecological protected area in Taiwan. The refuge covers two islets and its surrounding 100m maritime space.

Wangan Island in Penghu County is currently the only remaining green sea turtle habitat in Taiwan. The Penghu County Government announced on January 17, 1995 that the beach of Wangan Island was designated as the green sea turtle nesting refuge. It is currently the only green sea turtle nesting refuge in Taiwan. 6 spawning beaches for green sea turtle are designated as wildlife refuges, which are 23.3 hectares total.

Chihyu and Fanzai Rock are located in Beiliao Village, Huxi Township, Penghu County, and in the northeast side of the main island of Penghu.
Chihyu—At high tide Chihyu is a small island completely cut off, while it is connected to the seawall in Beiliao by a basalt gravel causeway of about 350 meters in length and 50 meters in width that is only exposed at low tide.

Fanzai Rock—Located about 1 kilometer southeast of Chihyu on the wave-cut platform, an irregular area of peridotite xenoliths embedded in basalt rock measures about 100 meters by 3 meters by 1.5 meters, with a feature of high-pressure minerals and the highest distribution density in Penghu. Fanzai Rock is very precious.

The whale cave and crater lake ruins are located on the western side of Penghu's main island, Xiaomen Island, Xiyu Township, Penghu County.
Whale Cave—an erosion arch formed by sea erosion.
The high accessibility and easy observation of the complete sea arches, coupled with the whale like shape, have given rise to many legends, making it an extremely storybook basaltic sea erosion terrain in the Penghu Islands.

Crater Lake Ruins

Geological features of later basaltic lava flows overlying ancient craters.
From the crater lake remains section on Xiaomen Island, it can be observed that the sedimentary rocks contain peat, which is black in colour, and that the peat layer has a baked structure at the junction with the overlying lava. The lowermost layer shows a sulphur layer with the remains of a vent. The wall layer structure reveals the evolutionary history of the caldera, making the Xiaomen Island Crater Lake relics a rare and unique geological landscape.