Prince Charles, Camilla get royal tour of Washington

Britain's Prince Charles (3rdL) and Camilla, Duchess of Cornwall (C), visit the Martin Luther King, Jr., Memorial in Washington, March 18, 2015. The couple is scheduled to visit cultural and educational sites over the next three days. [Photo/Agencies]

In the morning, the British royal couple was joined by two civil rights leaders for their tour of the Martin Luther King Jr. memorial - the Rev. Jesse Jackson, a protege of King; and Rep. John Lewis of Georgia, who marched in the "Bloody Sunday'' demonstrations for minority voting rights 50 years ago.

Charles and Camilla spent about 20 minutes touring the King memorial. The couple paused briefly to read some of King's quotations about the civil rights movement that are engraved in stone.

"Darkness cannot drive out darkness, only light can do that. Hate cannot drive out hate, only love can do that,'' read one quotation where the royal couple paused to see King's words from 1963.

The royal couple also visited the Lincoln Memorial, where they were greeted by historians Michael Beschloss and the Pulitzer Prize-winning Doris Kearns Goodwin, author of "Team of Rivals: The Political Genius of Abraham Lincoln.''

After a day of playing tourist, Charles delved into the nitty-gritty of environmental policy, speaking about the dangers of accumulating plastic waste in the world's oceans.

He gave a 10-minute speech to a joint meeting of the Global Ocean Commission and the International Sustainability Unit, a charitable group established by the prince to address environmental concerns.

He cited a study estimating that by 2025, there will be one ton of plastic in the oceans for every three tons of fish.

"Although the evidence surrounding the links between plastic waste and human health are not yet clear, I would tentatively suggest that they are unlikely to be beneficial,'' he said dryly.