Condensation means moisture got inside
Fog under the crystal means moisture crossed the case boundary. The source may be a crown, crystal, gasket, caseback or other sealing issue.
Do not use heat to dry the watch
Hair dryers, ovens and other heat tricks can damage components and do not properly address water trapped in the movement.
Damage can spread
Steel components, dial feet, hands and movement surfaces can corrode. The earlier a wet watch is opened and evaluated, the better the chance of limiting secondary damage.
Water resistance after repair
The original rating cannot simply be assumed after a moisture event. Case condition, seals and testing determine what can responsibly be represented.