Why Germany's Hallig islands are unique

Let's start (relatively) big and end very small. In terms of area and population, Langeness is the largest of the 10 Hallig islands on Germany's North Sea coast. It is about ten kilometers (6.2 miles) long and just under 1.5 kilometers (0.9 mi) wide. Around 110 people live on 18 "Warften" — the name given to the artificially raised mounds on which the houses stand.

The mounds with houses on them are the only part of the Hallig islands not flooded during a storm tide. The largest part of the Halligen is covered by the sea in a phenomenon locals refer to as "land under" or "Land unter" in German. Islanders then stay in their houses, bringing their animals to the mounds. When the sea recedes, everyone returns to the land — until the next storm tide.

In this photo of Hallig Hooge, the second largest Hallig island after Langeness, you can see a dwelling mound with several houses. You may wonder why people build their houses so close to each other in such a vast landscape. The first strong storm tide reveals the answer — οnly the mound (the Warft) with the houses remains dry.

With an area of 5.7 square kilometers (2.2 mi), Hallig Hooge is just slightly more than half the size of Langeness but has about the same population — approximately 100 people. Hooge, however, has more guest beds: 480 to 230 on Langeness. Hooge's hotels and vacation apartments host more than 40,000 overnight stays per year. Those looking for an idyll need look no further.

Third place in our Hallig ranking goes to Gröde. The Hallig island is only about 2.5 square kilometers (0.9 miles) in size. Less than a dozen people live in four residential houses on the Knudtswarft mound. On the second dwelling mound, the Kirchwarft, stands a church. There is also a small cemetery and an empty school, which includes an apartment for a teacher.

The Hallig Oland has a surface area of only two square kilometers (0.7 miles). However, it has significantly more inhabitants than Gröde — about 20. They live in a total of 18 houses on the Olandwarft mound. It's also a great vacation spot: After all, there are over 40 guest beds, a community center with a library, a church and a restaurant. What more could you want?

With an area of just under two square kilometers (0.7 miles), the Hallig island Nordstrandischmoor is nearly the size of Hallig Oland. But it has four mounds, just over 20 inhabitants, and one of the smallest schools in Germany with only a handful of students. Overcrowded classes are certainly not a problem here.

A big house for a small Hallig island. Hamburg Hallig is only about one square kilometer in size — and uninhabited. But there is the restaurant "Hallig Krog", which is open from Easter to late October. The Hamburg Hallig is cared for by the Nature and Biodiversity Conservation Union (NABU). A bird warden is on duty here. Like other Hallig islands, the Hamburg Hallig is also a bird sanctuary.

Süderoog takes seventh place in our Hallig ranking with an area of around 0.6 square kilometers (0.2 miles). The area remains the same, but the population is growing. A couple moved here in September 2013 and have since had two children. On the Hallig, also known as the "heart of the North Sea" because of its shape, you can even get married. So, who wants to tie the knot?

Hallig Südfall is just over a kilometer long and barely wider than 600 meters (1968 ft) at its widest point — about 0.5 square kilometers in area. There's one dwelling mound with one house — and even that's only half inhabited. A family lives there only during the summer. The Hallig is a bird breeding area and can be visited on a guided tour, via horse and cart across the mudflats.

With an area of 0.09 square kilometers (.05 miles), Norderoog lands — appropriately — in ninth place. It is the only Hallig without a dwelling mound. Instead, there's a pile dwelling for a bird keeper who does not currently live there. No wonder, then, that the island is also called "Vogelhallig" (Bird Hallig). Outside the breeding season, you can explore the island by hiking across the mudflats.

On the smallest Hallig (0.06 square kilometers), Hallig Habel, you don't need to go looking for sights, because if you're not a bird, you're not welcome. Here, too, only a bird watcher keeps an eye on things. The keeper works from the only dwelling mound on the island, the Norderwarft. And that concludes our digital island hopping tour of the unique sea-level Hallig islands.