San Francisco scientists came across alguronic acid while researching microalgae, and soon after, Algenist was born. That was just a few years ago, and the line continues to pick up steam -- selling out in Sephora and on QVC. Instead of algae, Algenist products contain patented alguronic acid, the molecule that protects the algae cell. In a similar way, it protects skin cells from UV damage and stimulates the production of elastin, which helps with firmness.

Star product: Algenist Catalyst Alguronic Acid Power Treatment, $195. This new trio of serums contains the highest concentration of alguronic acid, and it works fast. In studies, skin looked brighter and tighter in 10 days.

Aerospace physicist Max Huber created La Mer to treat chemical burns he suffered in an accident -- and it worked. By combining fermented sea kelp, vitamins and minerals, he developed the line's signature "miracle broth" -- and the recipe remains the same 40 years later. Now that's the sign of a true cult favorite.

Star product: La Mer Creme de La Mer, $155, is the signature product. It has a rich texture and soothing effect.

Instead of researching any old marine ecosytem, Ahava focused on the most mysterious of all: the Dead Sea. The resulting products contain a patented combination of Dead Sea minerals called Osmoter, as well as other botanical ingredients and brown algae.

Star product: Ahava Age Perfecting Hand Cream SPF 15, $32. This new hand treatment protects with SPF 15 while brightening existing sun damage. It's not the slightest bit greasy, and it smells amazing.

For three generations, Phytomer products have been developed and packaged on the shores of Brittany, France. The formulations blend marine ingredients with other plant extracts, and the products feel amazing and really work.

Star product: Phytomer Celluli Attack, $105. The French are famous for cellulite treatments, and the results from this one are pretty major. After just 28 days, dimpling was half as visible -- largely thanks to sea grape and sea absinthium extracts.

H2O Plus has it all: skin care, bath and body, even shampoo and conditioner. And the vast range of products contains dozens of ocean-sourced ingredients from blue sea kale to plankton.

Star product: H2O Plus Aquafirm Micro-Collagen Eye Cream, $38. Packed with brown algae and marine microspheres (a deeply penetrating moisturizer), this works wonders on crow's feet.