SOUTH CAROLINA - The National Oceanic and Atmospheric Administration's largest oceanographic research vessel has returned to its homeport after the longest deployment of any ship in the agency's history.

NOAA Ship Robert H. Brown spent almost 800 days at sea during the 3½-year deployment. NOAA says the ship traveled almost 130,000 miles conducting scientific research and servicing buoys that collect environmental data.

The agency says the ship's tasks included a rapid response mission to observe the 2015-16 El Nino. It also took more than 1,600 measurements in the Atlantic and Pacific oceans, ranging from Iceland and Alaska to Antarctica.

The Robert H. Brown also surveyed more than 350,000 square miles of seafloor and conducted ecological assessments of fisheries off Alaska's Arctic coast.

The ship's homeport is Charleston, South Carolina.