Prince William meets President Joe Biden in Boston

The Duke of Rothesay, Prince William, greeted the U.S President Joe Biden at Boston's waterfront on Friday. 

This marked the final day of a visit by the British royals trying to focus attention on tackling environmental issues. 

William and his wife Kate kept the spotlight on climate and other causes since taking on the titles of the Prince and Princess of Wales after death of Queen Elizabeth. 

On Friday afternoon, William smiled brightly as he met Biden outdoors taking a brief stroll in the chilly weather before a private reunion at the John F. Kennedy Presidential Library and Museum.

White House spokeswoman, Karine Jean-Pierre told reporters before the meeting, "The pair were expected to discuss shared climate goals and prioritization of mental health issues." 

Later the same day, both husband and wife honoured winners of the Earthshot Prize, an award William established to recognize people working on solutions to problems caused by climate change.

"By supporting and scaling them, we can change our future," said William on stage at the black-tie ceremony. 

The royal couple also last visited the United States in 2014 when they were guests of then-President Barack Obama at the White House.

Their current trip came just days before Harry and Meghan looked set to steal the limelight at an awards ceremony in New York.