Sea salt is not more nutritious or any healthier than regular (table) salt, despite how it may be marketed. Made by evaporating ocean water, unrefined sea salt contains trace amounts of minerals, including magnesium, calcium, copper, and iodine, but not enough to matter.
Iodine is needed for proper thyroid function, a reason why the mineral was added to salt nearly a century ago. Yet sea salt is seldom iodized, and highly refined sea salt is virtually identical to non-iodized table salt. Some sea salts have larger crystals and thus less sodium per teaspoon than regular salt, however.
By the way, kosher salt is not nutritionally better than regular salt, either, and also typically has no additives including iodine, though, as with some sea salt, it has less sodium per teaspoon than regular salt due to its larger, irregular crystals. Basically, salt is salt but with some small nuances, mostly in taste and texture, not nutrition.
