Danube Arena, Aquatics complex in Budapest, Hungary

The Danube Arena is an aquatics complex in Budapest designed by Marcell Ferenc and built between 2015 and 2017. It has two Olympic-size swimming pools, a diving pool and a short-course training pool. There are 5,000 permanent seats, plus 8,000 temporary seats used for the 2017 World Aquatics Championships and dismantled afterwards.

The Danube Arena was first planned for the 2021 World Aquatics Championships, but when Guadalajara withdrew as 2017 host in February 2015, Budapest took over and the design was revised. The foundation stone was laid on 15 May 2015, and the building, designed by Marcell Ferenc, was handed over in February 2017, before the contract deadline. It hosted the 2017 World Aquatics Championships that July.

The arena's name was announced by government commissioner Balázs Fürjes on 2 February 2017, when the finished building was presented ahead of the contract deadline. Its pools are shared with the neighbouring Dagály Strandfürdő, so bathers and swimmers move between the two facilities. The venue has also hosted boxing, with the youth world championships in August 2018.

The Danube Arena stands on the Pest bank of the Danube in northern Budapest, beside the Dagály baths. A promenade, the Dagály sétány, links it to the Forgách utca station of metro line M3 for pedestrians. The Népfürdő and Vizafogó streets were renewed with the project, and the lower quay between Dráva utca and Árpád Bridge became the Moszkva sétány for walkers and cyclists.

The arena was first planned for the 2021 World Aquatics Championships, but when Guadalajara withdrew as 2017 host in February 2015, Budapest took over and the building was redesigned, partly because the original design was too small for a possible 2024 Olympic venue. The cornerstone was laid on 15 May 2015.