Sea Salt still contains trace minerals like magnesium, calcium, potassium, iodine, iron, manganese, zinc and selenium, where table salt has been stripped of all trace minerals. Additionally table salt has been bleached, and anti-caking chemicals have been added to prevent it from absorbing moisture. And you might be eating a pinch of sugar in that table salt as it is used to round out the flavour since the anti-caking chemicals can be bitter.

If your sea salt is staying dry in moist climate then I would suspect you might have chosen a big Corporate brand that is creating a sea salt under commercial production and adding ingredients to prevent moisture absorption. You have to be very careful choosing your sea salt because the food inspection agencies allow food additives (like anti-caking chemicals) to be added to sea salt without requiring manufacturers to list the ingredient if it is under 1% of the overall weight. You won't even know your consuming it!

If you are purchasing an artisanal sea salt like Saltwest, the likelihood is that you are actually going to get trace minerals from consuming it, and you won't be subjecting yourself to unlisted food additives. 

The reality is that with our North American diet, 75% of the salt we eat comes from processed or prepared foods, 10% comes naturally in the foods we eat, like fish, and the other 15% comes from adding salt to foods when we are cooking. It's a smart move to use a natural sea salt when your seasoning dishes so you can limit your exposure to unwanted hidden ingredients. Experiment with new recipes and cook food from scratch as much as you can. That way you can control the levels of salt your body is exposed to. When all else fails, drink an extra glass of water to flush out the excess salt. Your kidneys will thank you. 

It's a good idea to find a local sea salt producer, ask some questions and get informed about how they make their sea salt and what they put in it. 

Staying Salty