Bermuda is a group of low-forming volcanoes located in the Atlantic Ocean, near the western edge of the Sargasso Sea, roughly 578 nautical miles (1,070 km (665 mi)) east-southeast of Cape Hatteras on the Outer Banks of North Carolina and about 594 nautical miles (1,100 km (684 mi)) southeast of Martha's Vineyard of Massachusetts. It is 898 nautical miles (1,664 km (1,034 mi)) northeast of Miami, Florida, and 667 nautical miles (1,236 km (768 mi)) from Cape Sable Island, in Nova Scotia, Canada. The islands lie due east of Fripp Island, South Carolina, west of Portugal and north of Puerto Rico.