Installing Floor In Aluminium Boat Installing Engineered Wood Floor - What To Use To Fill Voids In Subfloor Before Installation?

Installing Engineered Wood Floor - what to use to fill voids in subfloor before installation? - installing floor in aluminium boat

I am installing an engineered wood floor in a room upstairs. It currently enjoys an underground plywood quite interesting. However, there are holes and gaps in the basement. What product should be used to cover these areas? It would work ceramic tile adhesive? The differences between the plywood (maybe 1 / 8 "CAP) must register and complete?

Thank you!