BOAT-COMPARATOR Guide

Does Recreational Boat Noise Really Disturb Dolphins?

Engine noise, sudden acceleration, sonar: what the scientific research says about the effect of recreational boat noise on dolphins and marine wildlife, and how to sail with a lighter acoustic footprint.

Underwater noise is often framed as a problem for container ships and oil platforms. But recent research increasingly looks at a much quieter-seeming, yet far more widespread, coastal summer source: recreational boat engines.

Sound behaves differently underwater

Sound travels roughly four times faster in water than in air, and much further. An engine that sounds discreet from the cockpit can still be audible several hundred metres underwater, in a frequency range (roughly 100 Hz to 10,000 Hz) that overlaps directly with the range dolphins and many fish use to communicate, hunt and navigate.

What recent studies show

A 2019 review covering the full body of scientific literature on ship noise and marine mammals concludes that such noise can mask essential communication signals, drive animals away from otherwise favourable habitat, trigger stress responses, and in the most extreme cases cause temporary or permanent hearing loss (Erbe et al., Frontiers in Marine Science, 2019). More specifically on recreational boating, one study measured how leisure boat traffic altered bottlenose dolphins' signature whistles — the individual acoustic "name" each dolphin uses to be recognised — using it as a biological indicator of disturbance (study on an acoustic bioindicator of leisure boating disturbance, PeerJ, 2025).

Why the small boat matters too

Unlike a cargo ship passing once, a RIB or a day cruiser can cross the same stretch of coast several times in a single day, during the very season when local wildlife is breeding or feeding — and it is exactly this repetition, multiplied across dozens of leisure boats on the same stretch of water, that researchers point to as the real driver of impact on coastal populations.

Sailing with a lighter acoustic footprint

Slow down when approaching a group of dolphins or turtles instead of speeding up to "keep up", keep a reasonable distance without sharply changing course toward the animal, and cut the engine if the chance to watch them at idle presents itself: our guide to watching dolphins and turtles without disturbing them covers the right distance and behaviour. Marine protected areas often impose speed limits for exactly this reason — a useful benchmark even outside their boundaries.

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