Gunite
Also called: concrete pool, gunite shell, shotcrete.
Gunite is the structure of a concrete pool: concrete sprayed over a steel rebar frame to form the shell. Plaster is the finish troweled on top of that shell, so a plaster pool is a gunite pool and the two are not competing choices.
Why it matters
Gunite is built in place, so it can be any shape, any size, any depth, which is why custom pools, vanishing edges and deep diving wells are gunite. The shell is the longest-lived of the three in-ground types, 50 to 100 years, but the finish on it needs resurfacing and the surface is the hungriest for chemicals and brushing. The day it is sprayed, every depth, step and bench becomes permanent, so settle those before the pre-gunite inspection. In Florida, even a drained gunite pool can lift without a working hydrostatic relief valve.
In numbers
Gunite is sprayed in a day and then wants 7 to 14 days of curing, kept damp. A shell that dries too fast develops micro-fractures.