The site had already outlived three sets of ambitions. The Luftwaffe began developing Brand-Briesen Airfield in 1938. The Red Army took it in May 1945 and then stayed, adding a second runway and hardened, nuclear-resistant command and control facilities for a fighter regiment — a Soviet forward base an hour's drive from West Berlin.

German reunification in 1989–90 came with an agreement that Soviet forces would be out of the country by 1994. The federal government took full ownership of the airfield in 1992, and CargoLifter bought it to build airships on. When the company collapsed a decade later, the hangar simply stood there. It was open to visitors, who came to look at the inside of an enormous, immaculate nothing.

In June 2003 the Malaysian corporation Tanjong bought the hall for €17.5 million, €10 million of which came as a subsidy from Brandenburg. The building permit arrived on 2 February 2004, and Tropical Islands opened on 19 December 2004 — mid-December, in Brandenburg, which was very much the point.

Inside, the air is held at 26 °C and about 64 percent humidity, every single day of the year. There is a Tropical Sea: a 140-metre pool covering 4,400 square metres at a uniform depth of 1.35 metres, edged by 200 metres of sand. There is a Bali Lagoon with fountains, whirlpools and a current canal. A village of replica buildings from Thailand, Borneo, Samoa and Bali sits under the roof, and a 27-metre tower drops four water slides into the middle of it. Outdoors, the Amazonia area adds more than 35,000 square metres of pools, sunbathing lawn and beach volleyball.

The rainforest was the part nobody had modelled properly. Around 50,000 plants of some 600 species went in beneath a steel roof that turned out to block most of the light they needed. Photosynthesis stalled and the palms sulked.

The fix, installed in October 2005, was a 20,000-square-metre panel of UV-transparent ETFE film set into the southern face of the dome above the South Sea bathing area — a window of two full hectares, letting unobstructed daylight down onto the beach and the vegetation behind it. The plants have grown well ever since. In a hall 107 metres tall that matters more than it sounds: the greenery has had two decades to climb, and it is no longer decorative shrubbery.

Commercially, the early years were bleak. The resort needs roughly 1.25 million visitors a year to operate cost-effectively; in 2005 it lost somewhere between €10 million and €20 million, and by October 2006 had drawn about 600,000 people. The diagnosis was largely geographic. Tropical Islands sits well outside Berlin in a corner of southern Brandenburg where average disposable income runs below the national figure, and there was not enough local money within easy reach. Management widened the catchment, marketing into Poland, restructured the ticket pricing and added places to sleep.

It worked. 2008 brought the resort's first profit, on 300,000 overnight stays, and a campsite went up beside the hall that year. A six-part sauna complex — the largest tropical sauna in Europe, with rooms modelled on the cave temple at Elephanta in India and on Angkor Wat in Cambodia — had opened in 2007 alongside a 4,000-square-metre children's area. The Spanish group Parques Reunidos bought the resort in December 2018. Around 600 people now work inside the hangar, which can take 8,200 visitors in a day.