| Official Name: | Costa Marques |
| Settlement Type: | Municipality |
| Pushpin Map: | Brazil |
| Pushpin Map Caption: | Location in Brazil |
| Coordinates: | 12.445°N -64.2272°W |
| Subdivision Type: | Country |
| Subdivision Name: | Brazil |
| Subdivision Type1: | Region |
| Subdivision Name1: | North |
| Subdivision Type2: | State |
| Subdivision Name2: | Rondônia |
| Subdivision Type3: | Mesoregion |
| Subdivision Type4: | Microregion |
| Subdivision Type5: | Metrop. region |
| Leader Title: | Mayor |
| Area Total Km2: | 4,987 |
| Population Total: | 18,798 |
| Population As Of: | 2020 [1] |
| Population Density Km2: | auto |
| Timezone1: | AMT |
| Utc Offset1: | -4 |
| Postal Code Type: | Postal code |
| Area Code Type: | Area code |
Costa Marques is a municipality located in the Brazilian state of Rondônia. Its population was 18,798 (2020) and its area is 4,987 km2.[2]
The city is located in the Guaporé River's right bank and the main attraction is Forte Príncipe da Beira (named after the Prince of Beira), which was built in 1786 by the Portuguese Kingdom to protect that region from the Spanish Crown.
The municipality contains 91% of the Serra dos Reis State Park.It contains 14% of the Serra dos Reis A State Park, created in 1996.It also contains 52.5% of the Rio Cautário State Extractive Reserve, created in 1995.