Is it normal to be naked with my cousin?

I am 17 years old and I spend a lot of time with my cousin. She is 18 years old. I love the feeling of nudity and am naked whenever I can be. My grandparents have a pool, so on hot days I meet my cousin there and go for a swim. Last week, my brother was at a friends house, so I met my cousin at my grandparents house. They were also out. I realised I didn't have a pair of swimmers, so I was going to swim in my underwear, but then I thought stuff it, and I decided to swim nude. When we got to the pool, I just took off my shorts and jumped in. My cousin was a bit shocked at first, but after about 10 seconds she also stripped off and jumped in. We had heaps of fun, and nothing sexual happened. When we had had enough, we dried off, and just stayed naked. We spent the rest of the day nude. We made lunch together, ate, talked, watched tv and played a board game. Our nudity was never mentioned, and it felt so natural. Every day since then we have been nude together, and I enjoy the feeling so much. We now swim nude always, and our relationship has opened up so much. We openly talk about everything now, and she has turned into my best friend. Is it normal that I do these things?