The causeway crossing to Mandø is the defining experience of a visit. The Låningsvejen is a 4-kilometre unpaved track across the Wadden Sea tidal flats that is passable by car only at low tide — roughly two windows of a few hours each day. At high tide it disappears entirely beneath 1–2 metres of seawater.
You can drive yourself in a standard car if you time it correctly and consult the tide tables. The more memorable option is the Mandøbussen, a tractor-pulled bus with oversized tyres that departs from the Wadden Sea Centre in Vester Vedsted and takes around 40 minutes to cross the flats. The view from the bus — water stretching to the horizon, the island emerging ahead, the occasional seal or wading bird visible on the sandbanks — is unlike anything else in Scandinavia.
The sensation of driving on what is technically the seabed, with the smell of salt and exposed shellfish and the sound of water draining away on either side, stays with you long after the island itself has faded.