Charlottenlund is the beach-suburb walk. Strandpark for the sand, the slot grounds for the trees, Skovshoved Havn for the fishing boats, and Arne Jacobsen's 1937 petrol station — now a working café — for the architectural punctuation. The Coast Line drops you ten minutes' walk from each.
Four kilometres along the shore, a hundred minutes. Charlottenlund S-tog is on the Coast Line — fifteen minutes from Hellerup. Walk east through the Charlottenlund Slot grounds; the 17th-c royal residence is now a Danish research institution (no public access to the building), but the grounds are open.
Charlottenlund Strandpark is a few hundred metres east — the slow-curve beach Copenhagen north-siders use in summer. Walk south along the sand to Skovshoved Havn, a small working harbour with a few fishing boats and a fish stall in season.
The Arne Jacobsen petrol station is on Kystvejen a short walk inland — the 1937 modernist station with the mushroom-canopy in white concrete, now restored as a working café. Sit outside under the canopy with a coffee; the Jacobsen design is the experience. Back south along the coast to the S-tog.