//
Photo: Elgaard, CC BY-SA 3.0 via Wikimedia Commons
A unique 30-km² artificially created island, completed in 1914 as part of the city's extensive fortifications. Until Dubai and the Japanese went crazy with this type of construction, it was the largest offshore artificial island in the world. The island was sold to a private company in 2001, but since it is a protected area the new owners must ensure public access to the island. This is handled by Spar Shipping's three to five daily departures during the summer months (120 kr — 30 minutes). The sailing is done via a charming old ferry — MS Langø — from the pier just south of the Nyhavn area, but the island's marina is also open for private yachts. The new owners maintain hostel-like accommodations on the island in the fortress' old soldiers quarters, which can be rented for 800 kr per room with eight bunk beds. There is also a restaurant with traditional Danish lunch and dinners from 80 kr and a kiosk. The owners arrange various activities like treasure hunts, tours and team building activities taking advantage of the old fortress and its history, but this requires larger groups.
Flakfortet, meaning sand-shoal fortress, is a sea fort located on the artificially built island of Saltholmrev, in the Øresund between Copenhagen and Saltholm. The island and fort are simply known as Flakfortet; the name of the island; Saltholmrev, meaning the reef near Saltholm, is seldom used.
© OpenStreetMap contributors
Another sea fortress that guarded the approach to Copenhagen. It is owned by the Danish scouts.
Ski slope on top of the huge "Amager Bakke" incineration plant. You can ski, hike, climb, walk up the steps, etc. Or you can just take the elevater up, order a drink at the rooftop bar and enjoy the great view of copenhagen.
Amager Beach
Probably the largest beach in the near vicinity of Copenhagen, artificially constructed some years back. Includes a large sand island and an inner lagoon. There is usually a good range of activities going on, even outside the bathing season, such as windsurfing, diving, water skiing, sea kayaking and some hugely popular beach volleyball fields. If you're visiting during winter you have a chance to show your inner Viking with winter bath on the New Helgoland pier.
If you are an ornithologist, nature lover, or just want some peace, it is harder to get further away from it all and still be this close to the city. Saltholm is a large island off the coast of Amager — and you will be hard pressed to find even a local who has visited, despite the fact that the island is closer to most of Amager than downtown Copenhagen. The island covers some 16 km², and is incredibly flat — the highest point being just one to two meters above the sea — hence the island is largely unpopulated as it is very prone to flooding during hard weather. Save the farms, that brings in over a 1000 cattle every summer to graze on the island. The main reason to visit is to enjoy the wetlands, peace, and the many birds, including some very rare species. There are also seal colonies on the southern end of the island. To get here you need to call the private fishing vessel, which doubles as a ferry out of the small marina near the Kastrup metro station, but you are more than welcome to visit, as long as you pay respect to the unique nature, and practice a healthy dose of leave-no-trace.
Another of Copenhagen's old fortifications, which has been turned into an attractive park. Other than the outline, moat, walls and a few buildings remaining, there is not much to see here in terms of history. But there are some nice views over the sound and you can venture into the open part of the catacombs and see bullet holes from Nazi executions during WWII. A stroll here is easily combined with a visit to Amager Strandpark (see Do section), but otherwise probably not worth the effort.
National Aquarium Denmark
Largest aquarium in Northern Europe with 20,000 fish and ocean animals from all over the world.