Caviana, the Ilha Caviana, is an island lying off the north coast of Ilha de Marajó in the delta lowlands at the mouth of the Amazon in the state of Pará, Brazil. The island forms part of the low-lying marajó várzea, the inundated land in and around the mouth of the Amazon River. The island is an excellent place to observe the tidal bore called the pororoca, where the Amazon river waters meet the incoming Atlantic tides and form a standing wave, and is a birdwatchers' haven.
Map of Caviana, Chaves - State of Par%C3%A1, Brazil
References
Caviana Wikipedia(Text) CC BY-SA