Arrive in London, and embark National Geographic Orion, docked on the Thames. As the ship sets sail, take in views of the city's iconic landmarks and hear a presentation from a maritime expert on the importance of Portsmouth as a seaport.

Your first anchoring is England's maritime capital of Portsmouth. Delve into Great Britain's nautical history with a behind-the-scenes look at the perfectly preserved historic ships docked in the harbor, including the HMS Victory. Wander the city's atmospheric waterfront this afternoon, and perhaps stop for a pint at a traditional pub. Opt to venture through the English countryside to Southwick House, the Allied headquarters during the D-Day landings. You have exclusive permission to enter the fascinating D-Day Map room.

Dock at Alderney and take a walking tour of the island to learn about its important role in WWII under German occupation. Then, weather permitting, kayak across surrounding waters in search of migratory seabirds: puffins, gannets, and lesser black-backed gulls. After lunch, sail to nearby Sark. Take in the colorful sights and intoxicating scents of La Seigneurie Gardens. The coastal paths of Alderney are perfect for heading off on your own to cycle or hike with stops at must-see viewpoints. On Sark, explore the blooming headland of the Gouliot Caves.

Enjoy breakfast on deck as your vessel navigates the River Dart en route to Dartmouth, a colorful town that cascades across a steep riverside hill. In small groups, discover the guardrooms, battlements, and winding passages of the 14th-century Dartmouth Castle. Spend the rest of the day exploring Dartmouth’s lively lanes on your own. If you’re a mystery book fan, don’t miss a visit to Greenway House for a curator-led look at Agatha Christie’s house and gardens.

According to Arthurian legend, the Isles of Scilly are all that remain of Lyonnesse, a lost land off Cornwall's coast that is said to have vanished into the Atlantic. Discover Tresco Island and the world-class Tresco Abbey Gardens, where a surprising variety of tropical plants flourishes. Then stroll the village of Tresco, or join naturalists for a nature walk, spotting the flora and fauna of these mythical islands.

Beautiful Skomer Island overflows with wildlife. Hop on a Zodiac to spot whales, dolphins, and seals. This afternoon stretch your legs along Pembrokeshire Coastal Path, which winds along the cliffs and pristine beaches surrounding Fishguard. Or, spend the afternoon discovering the prehistoric archaeology of Pembrokeshire, the area that yielded the stones for Stonehenge. Or, venture to St. David's Cathedral for a guided walk of the lovely little town, before dinner ashore in Fishguard. This evening enjoy a special dinner in a 13th-century castle in the incredible Pembrokeshire countryside, complete with a private musical performance.

Dock at Holyhead and take a scenic drive to Snowdonia National Park. There are river gorges, waterfalls, lakes, and valleys to explore, whether you are coming for pulse-raising activities or for simply standing and admiring the Snowdonia Mountains. Or, visit Angelsey, a recognized GeoPark, to hike or cycle past intriguing rock formations. Enjoy a festive musical celebration before setting sail to Dublin. 

Wake up in Dublin and disembark after breakfast on-board. Transfer to the airport for flights home.