The Isthmus of Panama, coextensive with the republic, is the whole neck of land between the American continents; in another use the term " Isthmus of Panama " is applied to the narrow crossing between the cities of Colon and Panama, the other narrow crossings, further east, being the Isthmus of San Blas (31 m.) and the Isthmus of Darien (46 m.).
Wide at the widest point, with a maximum depth of 120 ft., protected on the sea side by Chiriqui Archipelago; immediately east of Colon, at the narrowest part of the isthmus, is the Gulf of San Blas, 20 M.
The only regular ranges in Panama are in the extreme western part where the Costa Rica divide continues into Panama, and, immediately south of this and parallel to it, the Cordillera of San Blas, or Sierra de Chiriqui, where the highest peaks are Chiriqui (11,265 ft.) and, on the Costa Rican boundary, Pico Blanco (11,740 ft.) and Rovalo (7020 ft.) there are two passes, 3600 and 4000 ft.
South of Bahia Blanca is the sheltered bay of San Blas, which may become of commercial importance, and between the 42nd and 43rd parallels are the land-locked bays of San Jose and Nueva (Golfo Nuevo) - the first as yet unused; on the latter is Puerto Madryn, 838 m.
Lying off San Blas in the broad entrance to the Gulf are the Tres Marias, and directly west of Colima, to which it belongs, is the scattered volcanic group of Revillagigedo.
The larger ports for foreign trade are Vera Cruz, Tampico, Progreso, Carmen and Coatzacoalcos on the Gulf coast, and Guaymas, La Paz, Mazatlan, Manzanillo, San Blas, Acapulco and Salina Cruz on the Pacific coast.
West of the Blas river a similar reversed fault forms the boundary between the lower Tertiaries and the pre-Tertiary rocks of the Himalaya, while between the Sutlej and the Jumna rivers, where the lower Tertiaries help to form the lower Himalaya, the fault lies between them and the Siwaliks.
He translated Gil Blas, adopting more or less seriously Voltaire's unfounded suggestion that Le Sage plagiarized from Espinel's Marcos de Obregon, and other Spanish books; the text appeared in 1783, and in 1828 was greatly modified by Evaristo Pena y Martin, whose arrangement is still widely read.
They are most violent from San Blas southward to the Guatemala frontier, and some of the Spanish towns on or near this coast have suffered severely.
The principal bays on the mainland coast are Olas Atlas, which is the harbour of Mazatlan, San Blas, Banderas, Manzanillo, Acapulco, Salina Cruz and Tonala.