Does a sun tan automatically mean sun damage?

It is damaging your skin. Any time the natural color of your skin gets darker, your cells are actually mutating in an attempt to ward off the UV radiation. Your application of sunscreen is very good, as long as you are remembering to reapply every thirty minutes, especially since you are in the water.

So, yes, a suntan is automatically damaging to your skin.

Yes it does, no sun screen is perfect, it can only block so many of the UV rays but it is (of course) better than nothing. You can try using a higher SPF and see if that helps, I always wear much higher than I need and make sure I'm putting it on at least 30 minutes before I go outside. You should also make sure you are applying enough product, if you are wearing a bikini you should be using about 1oz (golf ball sized), if you don't put enough on you can cut the effectiveness of the SPF by up to half of what's labeled on the bottle. I went to Magic Mountain yesterday, I applied an SPF 70 before even getting dressed and after all day (and no reapplying) I have zero burns and zero tan.

A suntan doesn't automatically mean you have damaged your skin. Some people just get a tan even with sunscreen on. It may just be your body reacting to you being in the sun all the time. If you get too much of tan or never wear sunscreen or protect yourself then yes I would advise you to take better care as it might in the long run develop into become something more serious.

So for your problem I do not think you have too much to worry about, as you seem to be taking precautions and various other things. Just keep up with what you are doing, and maybe if you are swimming a lot and when you have to sit down, sit in the shade and if not then wear a long sleeved shirt over the top to at least keep the sun off you for a short while (I was told this by my doctor cause I had the same problem)

Hope I was of some help ... ^_^

Even with sunblock, you will get tanner. However, there is no such thing as a safe tan because a tan itself is your skin trying to protect itself from the UV rays its being exposed to. As long as you keep up with the SPF etc, you should be fine.

A tan is the skin's response to sun damage (caused by Ultraviolet radiation).

Yes, all tanning is damage. You should probably get a higher SPF, and don't forget to reapply it.

a tan is the melanin in your skin darkening, but i don;t remember if its from the ultraviolet light or something else

the spf should protect you though, i mean, thats what its for :)