Adriaan Marais and Marinus du Plessis launched their personal watercrafts from the Ship Creek boat launch ramp Friday morning intending to ride them about 13,000 miles to Miami.
The adventure, if successful, would set a world record for distance traveled on a personal watercraft.
Marais and du Plessis, both from Pretoria, South Africa, say they'll follow the west coast of North America south to the Panama Canal before crossing to the Atlantic Ocean and heading up to Miami.
No support craft will travel with them.
The pair will have only the gear and fuel they can carry onboard, about 180 pounds per watercraft including extra fuel, du Plessis says.
They hope to get as much as 250 miles between fuel fill-ups. Unfamiliarity will add to the challenge.
"We don't really know the (North American) coast," du Plessis said.
"We've got no idea what to expect." He admitted he was nervous.
The pair are not rookies at such distance travel, however. They say they once traveled 5,000 miles along the coast of Africa from Kenya to Cape Town, South Africa.
They intend to post occasional updates about this journey on their Web site, www.13000miles.com.
They hope to reach Miami in about three months.