The Giffords set sail from the coast of Washington state in the US in 2008. Their trip, which took one year to plan, has encompassed 48 countries and territories over the past decade.
With life jackets firmly secured, the Gifford siblings sailed through San Francisco at the start of their journey: four-year-old Siobhan (left), six-year-old Mairen (middle) and nine-year-old Niall (right) could not swim at the time, though they would soon take to the water like fish.
Physical books and e-books have played a big role in home schooling the Gifford children, seen here after a beach combing expedition in Mexico early in their trip. "We are living basically on a field trip," says father Jamie.
The Gifford children made friends in Mexico during an early stop in their 10-year journey.
The family -- seen taking in a home-cooked meal in Papua New Guinea -- has enjoyed experiencing other cultures through their cuisines and learning recipes.
During their travels, the Giffords have exchanged time on the boat and other acts of goodwill for recipes and cultural experiences. Here Jamie helps a local in Papua New Guinea repair a sewing machine.
Sailing Totem takes a much-needed break in Tonga. Built in 1982, the fiberglass-made sailboat was purchased for $190,000 by the Giffords in 2007. It comes equipped with a 75-horsepower engine, and is fitted with three bedrooms and two bathrooms.
Sailing Totem is where the Giffords' sleep, even when docked on land. "The boat is our home," says mom Behan. "It would be very strange to check out of our home and into a hotel when our home is right there."
Mairen spots whales at a lagoon off the Hermit Islands in Papua New Guinea.
A tree-kangaroo perches on Siobhan's head in Ninigo archipelago, Papua New Guinea
Freediving without a tank is something the family has become adept at, as shown by this photo taken at a coral reef in the Bahamas.
Behan Gifford -- seen freediving off Gili Air, an island near Lombok, Indonesia -- can achieve depths of 50 feet without a tank, while husband Jamie freedives 65-feet deep.
The Gifford family looks out onto the Andaman Sea in the Indian Ocean.
The family has seen extraordinary beaches during its time at sea, including Isla San Francisco, an island off Baja California in Mexico.
Jamie mixes with locals at Gamfi island, part of the Raja Ampat archipelago in Indonesia.
The family poses in the state of Malacca in Malaysia in 2014. Niall (center with hat) recently moved on from life at sea to pursue his university degree in Portland, Oregon.