For a hit of maritime air, take a cruise on the Wattenmeer sea, a World Heritage-listed maritime national park between the mainland and North Frisian islands. The destination for most tours are the Halligen: glorified sandbanks whose 1–2m elevation above the high-water mark permits minor agriculture in between storm surges. Small wonder villages on the largest island, Pellworm, are ringed by defences like prehistoric earthworks. Ferry operator NPDG (04844 753, faehre-pellworm.de; €19.50 return from Husum, €10.50 from Nordstrand) operates several ferries a day to Pellworm from Nordstrand harbour 15km northwest of Husum. Departures are coordinated with the timetable of bus lines #1047 and #1091 from Husum; tourist information in Husum has ferry timetables. Alternatively, from mid-April to October, Adler Schiffe (01805 12 33 44, adler-schiffe.de; €20.50) runs two tourist cruises daily to pretty, rural Hallig Hooge, the so-called King of the Halligen due to its huge size – seven square kilometres; embarkation is at Nordstrand. It also runs appealing trips to Arum and Sylt to approach the North Frisian islands by the back door.