Guided seal-watching walks out from Le Hourdel, run by nature guides Arnaud Lengignon and Aurore Sartorius. The Pointe du Hourdel is where the Somme meets the sea and where several hundred harbour and grey seals haul out on the sandbanks as the tide drops — the largest colony in France, and genuinely reliable rather than a maybe.
Three routes are offered, from an hour and a half to two and a half hours, differing mainly in how far out towards the banks they go. Groups are capped at 25 per guide and the guides carry telescopes; the whole approach is built around watching the colony from a distance rather than walking up to it, which is both better ethics and better viewing, since disturbed seals simply slide off into the water.
Departures are from the bus shelter by the old school on the Rue de la Chapelle in Le Hourdel, and the time moves with the tide every day. Around €16 for adults and €8 for children aged five to fifteen. Wear something you don't mind getting wet to the knee.