"Still, whoever joins a discussion has the responsibility to correct the other participants' relevant misunderstandings,"

Griska, when you are right you are right.

DMcG, Obviously the Pier was built on tanks from definition 1. and had enough air for buoyancy.

tank
taNGk/
noun
plural noun: tanks

    1.
    a large receptacle or storage chamber, esp. for liquid or gas.
       the container holding the fuel supply in a motor vehicle.
       synonyms:        container, receptacle, vat, cistern, repository, reservoir, basin More
       "a hot water tank"
       a receptacle with transparent sides in which to keep fish; an aquarium.
       synonyms:        aquarium, bowl More
       "a tank full of fish"
    2.
    a heavy armored fighting vehicle carrying guns and moving on a continuous articulated metal track.