:D Other people were wearing wetsuits and all we had on were our bathing suits.
:( Other people were wearing wetsuits and all we had on was our bathing suits.
'suits' is plural:
Bathing suits are what we had on.
Bathing suits were what we had on.
The surf was about waist to chest high and glassy, which was fun.
The surf was about waist to chest high and glassy, which was very fun.
:D The surf was about waist to chest high, deep, and glassy, which was fun to swim in.
:D Mostly because all of us had become used to the water by then.
:( Mostly because all of us had become use to the water by then.
"used to", a predicate adjective, means, accustomed to, whereas "use", a transitive verb, means "bring into service", and it is always followed by an object (i.e. use it, used it, use them, used them) and never followed by "to".
Speakers tend to omit the sound [d] when pronouncing "used to". The reason being, "used to" ([ju:sdtu]) has three consonants in a row [sdt]. The first and last sounds, [s] and [t] are voiceless, whereas the middle sound [d] is voiced. [d] is the odd sound out, so speakers tend to deleted it, producing [ju:s'tu], which sounds like *"use to", but should always be written as "used to".