Google Maps has always had a few funny Easter Eggs which weren't that hard to find either. Unlike Mordor for example. Asking for walking directions across continents could result in Maps directing you to swim the seas or canoe over oceans.
Keeping with that tradition, Google is making sure you get an even better workout. Directions from the US to Europe no longer involved swimming the Atlantic Ocean.
Google has something else in mind now, just trek across the US, sail the Pacific, making a pit stop in Hawaii, to enjoy the sights perhaps.
You then land in Japan, but since it's a short trip from there to China, you can just take a jet ski over the sea.
Head north to Russia, traverse the largest country on the planet, visit Europe and you're there. Just 19,000 miles and 519 hours later, you'll arrive at the destination.