sub-aqueous (not comparable)
- Alternative form of .
- 2012, Andrew Martin, Underground Overground: A passenger's history of the Tube, Profile Books, →ISBN, page 87:
- [...] he'd been hoping to build a bridge over the River Nova in St Petersburg. The Russians would eventually decide to go under the river, but not before Brunel had shown the way, by building the first sub-aqueous tunnel in the world.