Thinking English while swimming

I have the honour to teach Nicolas, a ten-year-old boy from France for this whole week. As he has just changed from a French school to an international school, his English is as of those five-year-old. Never mind about that, he's cute and smart. He learns fast. 

For the first day, I had him design his own T-shirt with a fabric crayon. At the first look, it was horrible and I was thinking, "Would he wear this?" But after 20 minutes of drawing and colouring, viola! The T-shirt was brought to life! It was simply beautiful that left me with awe. 

Before I left, Nicolas' mom suggested swimming as part of the lesson to learn English. I was overwhelmed. Swim-and-learn-English? Is this a new lesson or what? I went online to search for games to play when one is swimming. There isn't much help. 

Finally, thank God for His creativity, I got the hint of finding something which could float for the boy to catch or read. And I came to the conclusion of having written papers inserted into clear empty bottles.

Before the game, I taught Nicolas about synonyms and when we reached the pool, I had all the bottles thrown into the pool. Nicolas had to swim to get a pair of bottles with the right synonyms. Eg. If he gets "beautiful" as the first bottle, he needs to find "pretty" and passed to me. The boy enjoyed the game while I enjoyed teaching. So, how about some synonyms in the pool?