Whale watching boat impact on whale surface behaviour

Whale watching is one of Iceland’s most unforgettable wildlife experiences, offering people the chance to witness the behaviours of incredible species like humpback whales, minke whales, white-beaked dolphins and occasionally harbour porpoises up close.

But how do these animals react when boats approach?

Over the summer 2025 season in Faxaflói Bay, dozens of sightings were recorded and analysed to better understand how whales respond to the presence - and proximity - of vessels. Here are some of the most common patterns observed, along with real-world examples.

1. Calm and Curious

Typical behaviour: Approaching the boat slowly, surfacing near the vessel, rolling or spy-hopping.

Boat distance: Usually 100–300 m or closer.

Possible interpretation: Tolerant or interested.

One afternoon, a lone humpback was observed resting near the surface as tour boats approached. Instead of moving away, the whale remained nearby, occasionally surfacing close to the vessels and even rolling onto its side - a behaviour that may indicate curiosity. The calm demeanour persisted despite the presence of three nearby boats.

A curious humpback getting a good view of the boats around (spy-hopping).

A humpback rolling and slowly waving it’s long pectoral fins.

2. Change of Direction or Speed

Typical behaviour: Altering course suddenly, increased swim speed, zig-zag patterns.

Boat distance: Often within 50–100 m.

Possible interpretation: Avoidance or mild disturbance.

Minke whales in particular showed this behaviour. In one encounter, two minke whales surfaced within 50 meters of the boat and immediately changed direction, swimming in the opposite way.

 Rare sighting of two Minke Whales traveling together.

One humpback was observed repeatedly shifting its swimming direction after three boats closed in within 100 m. The whale made at least four abrupt turns within 15 minutes, suggesting a possible low-level avoidance strategy.

3. Deep Diving

Typical behaviour: Frequent or prolonged deep dives, often with fluke visible.

Boat distance: Occurs at various distances, but more common with multiple boats nearby.

Possible interpretation: Attempt to avoid prolonged surface exposure near vessels.

One notable humpback was seen fluke-diving multiple times in a row with little time spent at the surface. As more boats gathered around, the whale increased the number and duration of deep dives. This pattern suggests a strategy to avoid surface interactions - possibly due to perceived pressure from the boats.

A humpback fluke deep diving next to a boat.

4. Energetic Displays

Typical behaviour: Breaching, tail slaps, pectoral slaps.

Boat distance: Can happen both near and far from vessels.

Possible interpretation: Communication, play, or signs of stress.

Although often seen as a crowd-pleaser, energetic surface activity might not always mean a whale is relaxed. In one case, a humpback began breaching repeatedly when three boats surrounded it within 100 meters. The breaching increased as boats approached and decreased once they left. While this behaviour may be natural, repeated displays in the presence of boats can be signs of agitation.

A humpback whale breaching in front of a boat.

On other occasions humpbacks can be seen breaching in the distance with no boats nearby and then stop once boats are in close proximity.

Powerful tail slaps from a Mother Humpback Whale in the presence of 4 boats.

White-beaked dolphins can often be rather curious and can often be spotted bow riding when spotted.

A pod of dolphins approaching the boat to do some bow riding.

5. Resting Disruption

Typical behaviour: Transition from logging (resting) to diving or moving away.

Boat distance: Typically occurs when boats come within 50 to 100 m.

Possible interpretation: Disturbance of natural rest cycles.

Humpback whales are occasionally observed logging at the surface - resting motionlessly in between dives. In one encounter, a mother whale and its calf had been logging for a long time on the surface close to the boat and then went for a deep dive and coming up in another direction, likely disturbed from its rest.

Mother Humpback and calf sleeping, just before diving away.

When Whales don’t seem to mind

Not all individuals react strongly to vessel presence - particularly when engines are lowered or boats maintain respectful distance. Often their behaviour does not change in the presence or absence of boats. One instance three humpbacks were observed bubble-net feeding intensely within 30 m of a stationary vessel. So focused on its foraging, one whale nearly brushed the side of the boat during a lunge dive—startling the passengers but showing no sign of stress or behaviour change.

A humpback coming in very close contact with a switched off boat.

A group of three humpback whales bubble net feeding right next to the switched off boat.

What Can We Learn?

The diversity in whale responses shows that not all encounters are the same. Species, group composition, individual personality, boat type, and approach distance all play a role in how a whale reacts.

Some animals appear relaxed even around multiple vessels, while others show clear signs of avoiding contact or signs of annoyance.

Respecting Their Space

These observations reinforce the importance of following whale-watching guidelines:

• Maintain at least 50-100 meters distance from cetaceans.

• Reduce speed near animals.

• Limit the number of vessels around a group.

• Watch for signs of avoidance or stress—and back off when seen.

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With responsible practices, whale watching can continue to be a powerful tool for education, tourism, and conservation !

Lenja Dunker