The Seabourn Odyssey makes its maiden voyage today as the first of three new ships set to triple Seabourn’s fleet by 2011. Accommodating 450 guests, the Odyssey is Seabourn’s largest yacht (as they insist on calling their vessels). Seabourn is also hailing the Odyssey as the first new luxury ship to launch in six years (um, tell that to Cunard).

Odyssey’s onboard spa is supposed to be the largest on a luxury vessel, spanning two decks. With a panoramic sliding glass wall, the spa features a thalassotherapy pool, seven treatment rooms and several 750-square-feet “villa suites” with private sunbathing balconies. In addition to four restaurants and a string of high-end boutiques (think Chanel, Dior and Hermes — the last of which will supply soaps to the suites), the Odyssey also has a private diamond showroom — where you’re welcome to buy, of course.

The Odyssey will embark on Seabourn’s first around-the-world cruise as part of its 2010 itinerary.