The main escarpment forms the boundary between the sea-level littoral and the inland plateau (planalto), which has a mean altitude of 500 to 1,300 metres (1,600 to 4,300 ft).

With an altitude of 2,255 metres (7,398 ft), Pico da Caledônia in Nova Friburgo is among the highest points in Serra do Mar.

Geologically, the range belongs to the massive crystalline rock platform that forms Eastern South America, and tectonically it is very stable.

A chain of national and state parks, ecological stations and biological reserves now protect the Mata Atlântica and its biological heritage, but acid rain, pollution, poachers, clandestine loggers, forest fires and encroachment by urban areas and farms are still causing active destruction, particularly in the areas around cities.

Several large metropolises, such as Vale do Itajaí, Curitiba, São Paulo and Rio de Janeiro are near the Serra do Mar.