The reef encloses a lagoon up to deep in its western part.

The western side of the atoll contains many of Aitutaki's important features including a boat passage through the barrier reef allowing for anchorage close to shore at Arutanga.

The site consisted of ancient, emerged coral reef covered by a thin layer of soil, with the Pearl Harbor entrance channel and naval reservation marking its western and northern boundaries, John Rodgers Airport ( HIA today ) to the east, and Fort Kamehameha on the south.

The western side of the island is lined with sandy beaches and an offshore coral reef which creates a large lagoon.

The blacktail reef shark ( C. wheeleri ), native to the western Indian Ocean, is now regarded as the same species as the grey reef shark by most authors.

Compared to sharks from French Polynesia or Micronesia, grey reef sharks from the Indian Ocean and western Pacific are not as aggressive and less given to displaying.

One long barrier reef forms the western side of the atoll.

Its western side has farus and reef patches.

The northern and western sides are one continuous barrier reef, and the eastern side is another.

Serranilla Bank () is a partially submerged reef, with small uninhabited islets, in the western Caribbean Sea.

Bajo Nuevo Bank, also known as the Petrel Islands (), is a small, uninhabited reef with some small islets, covered with grass, located in the western Caribbean Sea at, with a lighthouse on Low Cay at.

The island is situated on the leeward ( western ) side of Heron Reef, a fringing platform reef of significant biodiversity, supporting around 900 of the 1, 500 fish species and 72 % of the coral species found on the Great Barrier Reef.

A rocky reef, parts of which break the surface at low tide, extends for from the western end of the island.

In contrast, the western side is composed of reef and several distinct islands, notably the inverted V shape of Atafu Island in the north, Alofi, which extends into the lagoon from the western reef, and the L-shaped Fenualoa in the southwest.

The main islands in the group are Île Boddam, with the former main settlement, and a land area of 1. 08 km², and Île Anglaise ( 0. 82 km² ), both on the western rim of the reef.

Motu One ( Marquesan for " Sand Island "; ) is the name of a small sandbank with no vegetation located on the western edge of a coral reef.

The rocks are in the western part of a lagoon surrounded by a submerged coral reef, over which the waves break, and that extends east-west and north-south, with an area of roughly 5 km² within the rim of the reef.

The western and southern sides of the atoll have a nearly continuous submerged coral reef, with three main passes that lead in to the lagoon: Erappu Channel, Marok Channel and Eneneman Channel on the west side.

There is a long reef at the western end of the island, where large blue mussels may be raked or taken by divers.

In the 10 years following the Battle of Manzikert in 1071, the Seljuk Turks from Central Asia established themselves over large areas of Anatolia, with particular concentrations around the north western rim.

On Diego Garcia, the main plantations were located at East Point, the main settlement on the eastern rim of the atoll ; Minni Minni, north of East Point ; and Pointe Marianne, on the western rim, all located on the lagoon side of the atoll rim.

There are also several man-made fresh-water ponds resulting from excavations made during construction of the airfield and road on the western half of the atoll rim.

Its crater rim is barely recognizable as remnants mark portions of Powell Buttes, Gray Butte, and the western front of the Ochoco Mountains at Barnes Butte.

Lafayette is located on the western rim of this valley.

The plateau is separated from the eastern Andes by the thick Neogene sediments of the Sub-Andean Trough that runs along the northern and western rim of the Guiana Shield.

The volcano is topped by a mostly ice-filled crater about wide, with numerous peaks along its rim including the highest summit, Haakon VII Toppen, on its western side.

On the western rim of the mare is the palimpsest Yerkes.

The crater Apollonius W is located on the western rim of the mare.

Some consider the crater rim around the western end of Lyttelton Harbour, which runs largely north-south, to also be part of the Port Hills.

Like the rest of the American military establishment, the Air Force was in no way prepared for battle at the western rim of the Pacific.

The hut is located on the western rim of the cirque and stand below the Tyrolean Zugspitze Cable Car.

Attempts were made in the mid 1880s, 1898 – 1901 and 1913-1914 to mine sulphur from White Island but the last of these came to a halt in September 1914, when part of the western crater rim collapsed, creating a lahar which killed all 10 workers.

Nobile is attached to the western rim.

The Eurasian Treecreeper belongs to the northern group, along with the North American Brown Creeper, C. americana, the Short-toed Treecreeper, C. brachydactyla, of western Eurasia, and, if it is considered a separate species, Hodgson's Treecreeper, C. hodgsoni, from the southern rim of the Himalayas.

Lake Sakakawea State Park is the western terminus of the North Country National Scenic Trail which is a National Millennium Trail that crosses the northern rim of the continental United States to Port Henry, New York.

A large hospital at the western rim of the locality was built between 1898 and 1906 on the initiative of Rudolf Virchow.

Just to the west of the ridges is Hilbert W, a crater with a smaller crater overlying the western rim, giving it a pear-like shape.

The interior walls are multiply terraced, although less so along the western rim.

Other important highways in the valley include State Route 46 ( SR 46 ) and State Route 41 ( SR 41 ), which respectively link the California Central Coast with Bakersfield and Fresno ; State Route 33, which runs south to north along the valley's western rim and provides a connection to Ventura and Santa Barbara over the Santa Ynez Mountains ; and State Route 152 ( SR 152 ), an important commuter route linking Silicon Valley with its fast-growing exurbs such as Los Banos.

On the other hand, in the western rim of Peros Banhos, the island north of Île Verte was only a small sandbank at the time of Commander Robert Moresby's Survey in 1837, but now it is a medium-sized island covered with vegetation.

At the western rim of the Wannsee locality the Glienicke Bridge connects it with the City of Potsdam.

Emei sits at the western rim of the Sichuan Basin.