The twelve questions
1. Which seal species live in the Netherlands?
Two: the common (or harbour) seal (Phoca vitulina) and the grey seal (Halichoerus grypus). Both are true seals (Phocidae). About 19 seal species exist worldwide. → Species overview
2. How do I tell a common seal from a grey seal?
The common seal has a round head with a short snout and V-shaped nostrils. The grey seal is larger, with a cone-shaped, "horse-like" head, a long snout and nearly parallel nostrils. → 5 differences in detail
3. When is the best time to spot seals?
Around low tide, when sandbars dry out and seals come up to rest. The Waddenzee and the Delta give you a chance almost year-round, except in closed nurseries during pup season. → Spotting times
4. How long can a seal stay underwater?
Up to about 20 minutes. Seals have muscles that store oxygen — a kind of internal scuba tank — and can close their ears and nostrils. Average dive depth is 25 m; the deepest measured dives reach about 100 m. → Sleep & diving
5. What do seals eat?
Mostly fish: flatfish (plaice, flounder, dab), cod relatives, herring, sandeel, and to a lesser extent shrimp and squid. An adult animal eats 3–7 kg per day. → Diet & hunting
6. When are pups born?
The common seal gives birth in June and July, at or near the water; the pup can swim almost immediately. The grey seal gives birth between November and January, with a white fluffy coat; the pup stays on land for about three weeks. → Reproduction
7. What do I do if I see a seal on the beach?
Keep at least 30 metres distance, do not touch the animal, keep dogs on the leash, and call a seal warden. Since the Dutch Seal Agreement, only trained wardens may intervene. → Pup-found protocol
8. How old do seals get?
In the wild, on average 20 to 30 years. Females often outlive males. The oldest documented grey seal reached 46 years. → Lifespan
9. Do seals sleep underwater?
Yes and no. They doze in several ways: floating vertically with their nose above water ("bottling"), lying at the surface, or resting on the seabed with held breath. Breathing is consciously regulated, not reflexive — useful in the sea, dangerous in nets. → Sleep explained
10. Can you pet a seal?
No. Touching is forbidden under Dutch nature law and dangerous: seals bite, carry bacteria that cause severe infections ("seal finger"), and become extremely stressed by human contact. → Why not
11. Are seals dangerous to humans?
Not if you keep your distance. But a seal is a large predator with powerful jaws and sharp teeth; a bite causes serious wounds and infections. Keep at least 30 metres away. → Safety
12. Why did the grey seal return?
After the 1962 hunting ban the species could recover from British colonies. The first pups in the Netherlands were born in 1985; the Waddenzee now holds about 7,800 animals. → History
More in-depth articles
Want to go deeper? Our knowledge base includes full articles that pair an answer with biology or context. For example, the anatomy of a seal, how tides shape spotting times, or why rehabilitation has worked differently since 2020. The spotting map shows every location, and counts shows where the populations stand.