四分律行事鈔資持記 2.1251

2.1251

不犯三緣。皆非戲意。道行渡水，一也；沈水取物，二也；學浮防難，三也。準《注戒》，而下多浮字。掉臂畫水，浮法須爾，因而潛故。

The three circumstances of no violation are all without playful intent: traveling on the road and wading water is the first; diving into water to retrieve an object is the second; learning to swim to prevent danger is the third. According to the Annotated Precepts, below "and" (而) the word "swim" (浮) is added. Swinging the arms and splashing water is necessary for swimming technique, and thus one submerges.