A floating suspension bridge is a type of suspension bridge supported by towers built on floating pontoons which are tethered to the seabed. The design is intended to overcome the difficulties of building suspension towers in locations where the water is particularly deep. no such bridges have been built, but planning was done to build one in Norway, at Bjørnafjord, designed by engineer Ian Firth. The bridge was later turned into a floating pontoon bridge with a conventional cable-stayed bridge secured to bedrock.
See also Floating cable-stayed bridge Cable-stayed suspension bridge Intercontinental and transoceanic fixed links Strait of Gibraltar Straits of Tiran
References
Further reading Floating suspension bridges - Long span bridges - Research - Structural Dynamics - Department of Structural Engineering - NTNU
https://www.vegvesen.no/vegprosjekter/ferjefriE39/konferanse/teknologidagene2015/_attachment/1023556?_ts=14ff54620d0&fast_title=11+-+Johannes+Veie++Presentation+of+TLP-concept+Teknologidagene.pdf