What wetsuit means in practice
A wetsuit allows some water inside while its material provides insulation. Fit, coverage and thickness all matter. A thickness label alone is not a personal comfort forecast for a particular day.
An example to think through
A visitor compares two rental quotes listing the same thickness. One includes full coverage and accessories, while the other describes only the main suit. Ask for the actual equipment list and discuss the intended outing with the provider.
A common misunderstanding
A wetsuit is not designed to keep the wearer completely dry.
Underlying concept: PADI — Wetsuits. The example is an original YouDive study prompt, not a reported dive.