Permanent Hair Straightening?

I have relatively curly hair. If I brush it out it will be wavy, or I can crinkle it up when it’s wet so when it dries it’s full of big curls. I use a straightner because though I like my curly hair- I love straight hair. I feel that it looks better and it’s easier to brush and manage. My only issue is that by the end of the day I get these little waves in it and “fly-aways” where pieces start to get a mind of their own and try to curl up. Especially in summer with all the humidity in the air. My hair looks terrible when it comes in contact with water and if I’m ever out on a rainy day I freak out! I would love to be able to just get a little wet and not have to worry about my hair rising up. I’m contemplating a permanently straightening my hair at a salon. Where can you get this done? The only places I have that do hair is Walmart and Super-cuts. Haha. Will either of these places do what I want or will I need to look elsewhere? I know there is something about a relaxer vs the other sort of straightening that is permanent. Anyone get any of these done? How long does it last? How much does it cost? After the 1st few days (when you cant wash it) Can you go into the water (the beach or misty rain) and have your hair stay straight? I want to not have to worry so much about my hair further than the bathroom! Haha XD Thank you for reading! I look forward to the comments!