pontoons

noun
  1. 1

    A flat-bottomed boat used as a support for a temporary bridge.

  2. 2

    A floating structure supporting a bridge or dock.

  3. 3

    A box used to raise a sunken vessel.

  4. 4

    A float of a seaplane.

  5. 5

    A lighter or barge used for loading or unloading ships.

Source: https://en.wiktionary.org/wiki/pontoon, https://en.wiktionary.org/wiki/pontoons