Generally it is not too difficult to obtain accommodations offered by Airbnb, but this does not apply in its special offers: in such cases you have to be quick off the mark and you have to be imaginative. People wanting to spend a night surrounded by sharks, for example, have to compete for the honour by submitting – at very short notice – a message between 50 and 550 characters in length. What's more, the accommodation is only available between 11 and 13 April. Guests who manage to clear these hurdles will be rewarded with a fairly unique place for the night – a lodging in the Aquarium de Paris right next to the Eiffel Tower, namely in a glass-walled chamber fitted out according to plans by the design agency Ubi Bene and not only surrounded by three million litres of water but also encircled by 35 sharks taking a curious look at their new fellow dwellers. The sleepover will include a tour of the aquarium – the world's oldest – by the host, Fred Buyle, a world record-breaking freediver, underwater photographer and shark enthusiast. Once the unique overnight stays are over, the circular chamber will be used for its actual purpose, namely as an observatory for marine biologists to study the behaviour of the sharks.