Taitao Peninsula in the context of "South American Plate"

The Chile triple junction (or Chile margin triple junction) is a geologic triple junction located on the seafloor of the Pacific Ocean off Taitao and Tres Montes Peninsula on the southern coast of Chile. Here three tectonic plates meet: the South American plate, the Nazca plate and the Antarctic plate. This triple junction is unusual in that it consists of a mid-oceanic ridge, the Chile Rise, being subducted under the South American plate at the Peru–Chile Trench. The Chile triple junction is the boundary between the Chilean Rise and the Chilean margin, where the Nazca, Antarctic, and South American plates meet at the trench.

46°50′50″S 75°20′04″W / 46.84722°S 75.33444°W / -46.84722; -75.33444

The Tres Montes Peninsula (Spanish: Península Tres Montes, English: Three Hills Peninsula) is a southwestward projection of Taitao Peninsula which in turn connects to the mainland of Chile by the narrow Isthmus of Ofqui. The peninsula is situated in Aysén del General Carlos Ibáñez del Campo Region close to the Chile Triple Junction of the Nazca, Antarctic and South American plates.

The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca plate and the Antarctic plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates to the Southern coast of Chile. The Chile Ridge is easy to recognize on the map, as the ridge is divided into several segmented fracture zones which are perpendicular to the ridge segments, showing an orthogonal shape toward the spreading direction. The total length of the ridge segments is about 550–600 km (340–370 mi; 300–320 nmi).

The continuously spreading Chile Ridge collides with the southern South American plate to the east, and the ridge has been subducting underneath the Taitao Peninsula since 14 million years (Ma). The ridge-collision has generated a slab window beneath the overlying South America plate, with smaller volume of upper mantle magma melt, proven by an abrupt low velocity of magma flow rate below the separating Chile ridge. The subduction generates a special type of igneous rocks, represented by the Taitao ophiolites, which is an ultramafic rock composed of olivine and pyroxene, usually found in oceanic plates. In addition, the subduction of the Chile Ridge also creates Taitao granite in Taitao Peninsula which appeared as plutons.

The Chilean Coastal Range (Spanish: Cordillera de la Costa) is a mountain range that runs from north to south along the Pacific coast of South America parallel to the Andean Mountains, extending from Morro de Arica in the north to Taitao Peninsula, where it ends at the Chile triple junction, in the south. The range has a strong influence on the climate of Chile since it produces a rain shadow to the east. Because of this the vegetation growing on the seaward slopes is much more exuberant than in the interior. Compared to the coastal lowlands and the Intermediate Depression, it is sparsely populated with land use varying from protected areas to grazing and silviculture. The range is present in all Chilean regions, except for Coquimbo Region and Magallanes Region.

The Isthmus of Ofqui is a narrow isthmus that connects the Taitao Peninsula with the Chilean mainland. The isthmus is bounded in the south by the Gulf of Penas, in the north by the San Rafael Lagoon, in the west by the Taitao Peninsula and in the east by the Northern Patagonia Ice Field.

Much of the swampy isthmus is drained by San Tadeo River that flows in SSW direction to the Gulf of San Esteban.

The Gulf of Penas (Golfo de Penas in Spanish, meaning "gulf of distress") is a body of water located south of the Taitao Peninsula, Chile.

Presidente Ríos Lake (Spanish pronunciation: [pɾesiˈðente ˈri.os]) is located in the Aysén del General Carlos Ibáñez del Campo Region of Chile. It lies in the middle of the Taitao Peninsula.

While the lake's existence only became known in Chile in 1945, it appears to have been known by Chono natives, who led 19 survivors of HMS Wager (including Captain David Cheap and Midshipman John Byron) from Wager Island through it in 1742. The Chonos, who often had a hostile relationship with the Spanish, kept the lake secret from them despite serving the Spanish as maritime pilots. Despite official discovery in 1945, the lake was already known to seafarers from Chiloé.