rio de janeiro was discovered by portuguese explorer gonçalo coelho - after a three month voyage from lisbon in 1501, his fleet arrived off the south american coast, in what is now brazil. on new year's day in 1502 his expedition entered the bay.

the explorers named the bay they had discovered rio de janeiro (january river), falsely believing that they had found a river. the misnamed bay is now called baía de guanabara (guanabara bay).  

it is surrounded by several large mountains, some of which exceed 2,000 feet and are part of the serra do mar (ocean mountains) mountain chain. other geographical features include over a hundred islands of varying sizes scattered throughout. many of the islands are actually mountains, jutting up from the sea.