My Hobbies

I like to swim very much because it's very good for my health.
Swimming helps me feel more comfortable, more strong, and more supple.
I can have some friends swim together. --> I can swim together with some friends.
I'll talk to you about the most of my memories.   (or)--> I'll talk to you about one of my best/favorite memories. (sounds better)
That is once, I went to swim in Ha Long beach. --> One time/Once, I went to swim at Ha Long beach.
That day, I with two my friends swam from the seaside to the warning bouy yellow, the distance about five hundred metres.--> That day, my friends and I swam from the seaside to the yellow warning bouy. The distance was about five hundred meters. (metres- non-American spelling/ meter- American spelling)

Although, I knew it's very danger but, we still continued and finally we were success --> Although I knew is was very dangerous, we still continued and were finally successful.

That is the time I swam the farthest and I feel(felt) the happiest.
In summary, swimming is very good for our health.
Thanks you for reading !