The Inside Passage is a 1,000-mile waterway running from Puget Sound in Washington State to the Gulf of Alaska, threading between the mainland and a chain of islands that shelter it from the open Pacific. It is one of the most productive marine ecosystems on Earth — cold, nutrient-rich water that supports an extraordinary density of life at every level of the food chain.

For wildlife, it is simply one of the best places on the planet. Not in the way that requires a week of hiking to find a single bear track — in the way that means humpback whales surfacing 200 yards off the bow before breakfast, bald eagles perched on every other spruce tree, and brown bears visible from the ship's deck at the right time of year.

This guide covers what to look for, where to look, and when.

The Inside Passage is seasonal, and the wildlife calendar matters more here than almost anywhere else. The right species at the right time can make an Alaska cruise transcendent. The wrong timing means you see the landscape — which is spectacular — but miss the animals.

May is the beginning of the Alaska cruise season, and it is underrated. The humpback whales are arriving from their winter grounds in Hawaii, and the feeding frenzy that follows — bubble-net feeding, where groups of whales cooperate to herd and trap herring — is one of the most spectacular wildlife behaviors anywhere.

Brown bears are emerging from hibernation, often visible on beaches and tidal flats as they forage for early-season food. Bald eagles are nesting. The days are long — 18+ hours of daylight by late May — which means more time to watch.

Crowds are lower than peak season, and prices are lower too.

June and July are the most popular months, and for good reason. The weather is at its best (relatively speaking — Alaska is Alaska), the wildlife is abundant, and the salmon runs are beginning in the rivers.

Humpback whales are present in large numbers throughout the Inside Passage. Orcas — both resident fish-eating pods and transient mammal-eating pods — are regularly sighted. Brown bears are active and visible. Sea otters are common in kelp beds. Steller sea lions haul out on rocks throughout the passage.

This is also when the salmon begin their runs, which concentrates bears, eagles, and orcas in predictable locations.

August is arguably the best single month for wildlife in the Inside Passage. The salmon runs are at their peak — pink salmon, sockeye, and coho — and the bears are at their most visible, fishing the rivers and streams in numbers that can be genuinely staggering.

Whale watching is excellent. The days are still long. The weather is typically the most stable of the season.

The tradeoff: August is the most expensive and most crowded month. Ships are full, popular excursions book out weeks in advance, and the ports are busy.

September is the end of the cruise season and one of the best-kept secrets in Alaska travel. The salmon runs continue, the bears are in hyperphagia — eating constantly to build fat reserves for hibernation — and the fall colors are beginning in the higher elevations.

Humpback whales are still present. The crowds are thinning. Prices drop significantly. The weather is more variable, but the light in September — lower angle, golden quality — is extraordinary for photography.

Humpbacks are the signature wildlife experience of an Alaska cruise. They are large (40–50 feet, 40 tons), acrobatic, and remarkably visible — the blow (exhaled breath) can be seen from miles away, and breaching humpbacks are one of the most dramatic sights in nature.

Where: Throughout the Inside Passage, with concentrations in Frederick Sound, Chatham Strait, and Icy Strait. Glacier Bay National Park is a reliable location.

What to watch for: The blow first — a column of mist 10–15 feet high. Then the back rolling through the surface. If you are lucky, a breach — the whale launching its entire body out of the water — or a fluke dive, where the tail lifts clear of the water before a deep dive.

Bubble-net feeding: A cooperative hunting behavior where groups of humpbacks work together to herd herring into a tight ball, then lunge through the surface simultaneously. One of the most spectacular wildlife behaviors anywhere. Most common in May and June.

Orcas are present throughout the Inside Passage in two distinct populations with very different behaviors:

Resident orcas live in stable family groups and eat exclusively fish — primarily salmon. They are vocal, social, and often seen in large pods traveling together. They are not dangerous to humans.

Transient orcas (also called Bigg's orcas) travel in smaller groups and hunt marine mammals — sea lions, harbor seals, porpoises, and occasionally humpback whale calves. Watching transient orcas hunt is one of the most intense wildlife experiences in Alaska.

Where: Johnstone Strait (British Columbia) is the most reliable location for resident orcas. Transients are found throughout the passage.

Brown bears (the same species as grizzly bears — "grizzly" refers to interior bears, "brown bear" to coastal bears) are the apex predator of the Inside Passage ecosystem. Coastal brown bears are larger than their interior counterparts, fed by the extraordinary protein of the salmon runs.

Where: Visible from ships at tidal flats and river mouths throughout the passage. Anan Creek (near Wrangell), Pack Creek (Admiralty Island), and Fish Creek (Hyder) are the most famous bear-viewing locations. Most require a small boat or floatplane excursion.

When: Most visible in July and August during the salmon runs. May bears are emerging from hibernation and are often seen on beaches.

Bald eagles are so common in the Inside Passage that they become background noise within a day or two — which is remarkable, given that they are the national bird and were nearly extinct 50 years ago. They perch on spruce trees along every shoreline, soar on thermals above the fjords, and congregate in enormous numbers at salmon streams during the runs.

Where: Everywhere. Sitka has one of the highest densities of bald eagles of any city in North America.

When: Year-round, but most visible during the salmon runs when they congregate at streams.

Sea otters were hunted to near-extinction in the 18th and 19th centuries for their extraordinarily dense fur. They have recovered significantly in Alaska and are now common in kelp beds throughout the Inside Passage.

They are endearing animals — they float on their backs, wrap themselves in kelp to keep from drifting, and crack shellfish on their chests. They are also a keystone species: their predation on sea urchins keeps the urchin population in check, which allows kelp forests to thrive.

Where: Kelp beds throughout the passage. Sitka Sound and Glacier Bay are reliable locations.

Steller sea lions are the largest of the eared seals — males can reach 11 feet and 2,500 pounds. They haul out on rocks and small islands throughout the Inside Passage in large, noisy colonies.

Where: Rock outcroppings and small islands throughout the passage. The South Marble Islands in Glacier Bay are a famous haul-out site.

Glacier Bay is the crown jewel of Alaska cruise wildlife viewing. The park encompasses 3.3 million acres of wilderness, and the cruise through the bay — typically a full day — passes through some of the most productive wildlife habitat in the Inside Passage.

Humpback whales are common in the outer bay. Brown bears are visible on the beaches. Mountain goats appear on the cliffs above the glaciers. Puffins nest on the rocky islands. And the glaciers themselves — 16 tidewater glaciers calving ice into the sea — are a spectacle that has nothing to do with wildlife and everything to do with the scale of the place.

Frederick Sound, between Admiralty Island and the mainland south of Petersburg, is one of the most reliable humpback whale locations in Alaska. The sound is a major feeding ground, and bubble-net feeding is regularly observed here in summer.

Icy Strait, near Hoonah, is another excellent whale-watching location and the site of the world's largest zip line (if that is relevant to your interests). Humpbacks are common, and orca sightings are not unusual.

One of the underappreciated aspects of an Alaska cruise is the wildlife visible from the ship itself — no excursion required. The key is to be on deck, particularly in the early morning and evening when the light is best and the ship is moving through productive habitat.

Bring binoculars. This is not optional. A good pair of 8x42 or 10x42 binoculars transforms the experience.

Watch the water surface. Whale blows are visible from a long distance. Scan the surface continuously rather than waiting for something obvious.

Watch the shoreline. Bears, eagles, and sea otters are often visible from the ship along forested shorelines and tidal flats.

Be on deck for glacier approaches. The approach to a tidewater glacier is one of the most wildlife-rich moments of an Alaska cruise — the cold, nutrient-rich meltwater attracts fish, which attract birds and marine mammals.

For more on planning your Alaska cruise, see our Alaska Cruise Guide and our comparison of Alaska vs. Caribbean cruises. For tips on booking wildlife excursions independently, see our guide to booking shore excursions independently.