Question about Casio F-91w-1yer

Casio (and many other digital watch makers) uses the term “30 m water resistant” according to the international ISO specification that applies to wristwatches. This does not mean it is suitable for swimming or diving to 30 meters depth. Instead the 30 m / 3 bar rating means the watch is designed to withstand splashing, rain, hand washing and incidental contact with water, but not prolonged immersion, showering, swimming or diving.