Sometimes, an expedition voyage can be full of surprises. San Diego to Vancouver may seem like an obvious itinerary along the West Coast but this expedition on Silversea’s Silver Explorer took us right off the beaten track.

In fact, apart from San Francisco, we only called at small, out-of-the-way ports, venturing inland along the Columbia River, which forms the border between Oregon and Washington State and around the forested San Juan islands, scattered off the coast near Seattle.

On day one, we anchored off the Channel Islands, a rocky archipelago some 20 miles off the California coast, a spot for camping, hiking and bird-watching. We hiked along the top of the windswept cliffs of Santa Cruz island, the hillsides ablaze with the yellow of wild mustard, not a soul in sight.

Monterey the following day was a-buzz with excitement as Nicole Kidman and Reese Witherspoon were in town, filming season two of Big Little Lies. There’s no shortage of celeb-spotting here; I joined a tour to Big Sur and Carmel, a staggeringly beautiful stretch of coastline, all pounding surf and long, empty beaches, the guide pointing out mansions of the rich and famous, including that of Clint Eastwood, Carmel’s former mayor.

We sailed under the Golden Gate Bridge at dawn. But even in San Francisco, Silversea added an expedition-style twist to the tours; as well as time in the city, we drove to Muir Woods to hike through primeval forest. Here, giant redwoods tower more than 600 feet, lime-green ferns drooping over rushing streams on the forest floor.

Leaving port, there was a celebratory atmosphere as we watched humpback whales breaching under the bridge; in fact, during the course of the 10 days, we saw more than 800 marine mammals, carefully logged in a survey by the team from British conservation charity ORCA.

After a day at sea, we were at the mouth of the Columbia River, the scenery completely different now: cargo ships laden with logs, dense pine forests, tiny coastal towns and the constant backdrop of the volcanic, snow-covered Cascades mountains. The most famous of these, Mount St Helens, was both intriguing and spine-chilling to visit. The world watched as the volcano exploded in May 1980, blowing off its whole top and side, causing untold devastation and killing 57. The guides told stories of the fateful day, which panned out like a disaster movie as the few who refused to leave their homes and lodges were pulverised by the blast, and millions of trees toppled like toothpicks in the shock wave. Their stumps are still visible, 38 years later, although the forest is growing back.

From Port Angeles, the gateway to the wild and beautiful Olympic Peninsula (which Twilight fans will recognise as the setting for teen vampire hit), I opted for another hike, again, through towering, old-growth forest, the trees festooned with lichen, the Sol Duc river rushing over mossy boulders and eventually cascading 48 feet over a cliff into a narrow canyon.

Mount Rainier, at 14,410 feet, is the highest of the Cascades mountains but sadly, was something of a let-down. We climbed in a bus past strip malls and casinos on the reservations, a chilling mist never lifting above the treetops. I assume the volcano was up there, as the air felt thinner and it snowed at one point, but it remained shrouded in cloud all day – the price you pay for such lush greenery.

Mount Rainier graced us with its presence for the rest of the trip as we explored the soporific archipelago of the San Juan islands, scattered across the water between the coast of northern Washington State and Canada’s Vancouver Island. At Anacortes, I joined a kayaking tour, inquisitive seals escorting us and a bald eagle swooping down to fish right in front of the kayaks. Later that day, in uncharacteristically blistering sunshine, Silver Explorer anchored off Friday Harbor, a cute little hippie town buzzing with art galleries, quirky shops and organic cafés, backpackers and weekenders spilling off the ferry from Seattle.

I absolutely loved this small ship; it underwent a full refit in 2017 and although petite, really is a Silversea vessel in microcosm, complete with butlers and all-inclusive service, with the added bonus of a seriously impressive expedition team. Dress code is completely casual – by day, at least, it’s walking boots and the smart Silversea Expedition rucksacks given to everybody. The food, needless to say, was superb, as you’d expect from Silversea.

The ship is all-inclusive, so you don’t need to budget for drinks, tips or excursions. Most days, only the brave enjoyed cocktail hour on deck, as evenings in May were distinctly chilly, but the San Juan islands were bathed in sunshine.

The Pacific Northwest is deservedly edging onto the cruise map, as Un-Cruise Adventures and American Cruise Lines call here, too. The region is, though, still relatively unexplored by cruise ships, even small ones, despite the dozens of vessels that summer just a bit further north, in Alaska. But with its rugged scenery, rich marine life and pretty little boho towns, what’s not to love?