[游泳姿勢]
doggy paddling 狗刨

學游泳從狗刨開始，不需要太多技能，只要兩手在胸前快速劃水，稍微蹬蹬腿就行(paddle your hands quickly in front of you and kick your legs a little)。

breaststroke 蛙泳

中文以其形似青蛙游水而命名，英文只以動作命名，stroke既可以指手腳的一次劃水動作，也可以指游泳姿勢和游泳方式。

The "breast stroke" is when you start with your arms together in front and draw them back in a wide circular motion.
蛙泳就是兩臂在胸前伸直，然后畫一個大圈劃水的泳姿。

backstroke 仰泳

仰泳的動作用英文可以這樣解釋：

The "backstroke" is when you float on your back and swing one arm at a time up over your head, then pull it down toward your body again through the water.
仰泳就是仰面浮在水上，兩臂輪流向后劃水的泳姿。

crawl 爬泳、自由泳

自由泳是最快的游泳方式。

When you swim in a crawl, you face down into the water and swing one arm at a time up past your shoulders, then pull it toward your body through the water.
自由泳時，臉朝下在水中，兩臂輪流劃水前進。

tread water 踩水

"Treading water" means moving your hands and feet around so that you don't sink.
踩水就是在水中手腳畫圈蹬踩，保持身體不沉。

[游泳安全]
lifeguard 救生員

一些泳池和海灘會有救生員執勤(have a lifeguard on duty)，他們在水邊看護，保障游泳者的安全。

游泳池通常還會貼著一些警示條例，比如：

Swim at your own risk.
在此游泳風險自擔

也就是說如果你受傷或者溺水，游泳池管理者概不負責。

Children under twelve must be accompanied by an adult.
12歲以下兒童須有成人陪伴

No running on the deck.
請勿在泳池邊奔跑

No horseplay.
請勿打鬧

所以在游泳館里，你不可以故意把水濺到別人身上(splashing people)、追追打打(chasing someone)、在水里打架(wrestling in the water)、把人扔進水里(throwing people in the pool)等。