It is not safe to swim in a number of different situations like - Beaches: -During a thunderstorm -During turbulent underwater currents -During large waves -During extreme cold and changing temperatures -When there are chances of the presence of dangerous animals in water like alligators Pools, Hot Tubs: -When there are no pool fences -When depths are widely varying -When the pool's chlorine level isn't being carefully monitored -When drain covers are missing -When algae is growing -When pool is at its full capacity General Waters -After alcohol consumption -When lifeguard is not on duty -In absence of adult supervision -After dark