Marine Hyaluronics

The name is either brilliant marketing or a genuine source of confusion, depending on how charitable you feel. The Ordinary Marine Hyaluronics contains no hyaluronic acid. None. The word “Hyaluronics” refers to the function — water-binding hydration — not the ingredient. What the product actually contains is a collection of marine-derived polysaccharides and bacterial ferment extracts that mimic HA’s moisture-holding properties through an entirely different molecular pathway. And for the audience this was designed for — oily and combination skin types who find traditional HA serums unbearably sticky — the distinction turns out to matter quite a lot.

DECIEM launched this in 2018, approximately two years after their Hyaluronic Acid 2% + B5 had become one of the bestselling serums in the brand’s history. The problem was predictable: HA 2% + B5 works beautifully for dry and normal skin, but its viscous texture and tendency to leave a tacky film made it a poor match for oily complexions. Rather than reformulate with lighter-weight hyaluronic acid, DECIEM went sideways. They built a hydrator from marine ingredients that would deliver the same outcome — skin that holds more water — through a completely different set of molecules.

The headline ingredients are Pseudoalteromonas exopolysaccharides and Pseudoalteromonas ferment extract, derived from bacteria that survive in extreme marine environments. These organisms produce polysaccharides and glycoproteins as protective mechanisms — compounds that happen to bind water with remarkable efficiency. Alongside them, Ahnfeltia concinna extract — from a Hawaiian red algae — acts as a natural water reservoir. The science is emerging but the mechanism is sound: these compounds form an ultrathin hydrating film that is functionally invisible on the skin.

Beneath the marine headline acts, the formula deploys a surprisingly comprehensive Natural Moisturizing Factor complex. Eleven amino acids — arginine, glycine, alanine, serine, valine, isoleucine, proline, threonine, histidine, phenylalanine, and aspartic acid — replicate key components of the skin’s own hydration system. PCA, sodium PCA, and sodium lactate complete the NMF mimicry. These are not exotics; they are ingredients that dermatological science has understood for decades. Their inclusion here is smart: the marine ingredients provide surface-level hydration while the NMF components support the skin’s intrinsic ability to hold moisture.

The texture — or rather, the near-absence of texture — is this product’s defining feature. It is as thin as water. It pours from the dropper like water. It absorbs into the skin faster than you can spread it. There is no viscosity, no slip, no film, no residue, no tackiness. If you have ever applied a product and genuinely wondered whether it did anything because it vanished so completely, you will have that experience here. For oily skin types accustomed to weighing every product in their routine against the fear of excess shine, this weightlessness is liberating.

The practical question — does it actually hydrate? — has a nuanced answer. Yes, but with caveats. The marine polysaccharides and glycerin do bind water, and the amino acid complex supports the skin’s NMF. Users with oily and combination skin consistently report that their skin feels more comfortable and less reactive when Marine Hyaluronics is part of their routine. But users with dry or very dehydrated skin consistently report that the hydration feels insufficient — that the product evaporates before it can meaningfully address their moisture deficit. This is not a product failure; it is a targeting decision. Marine Hyaluronics was built for people who need hydration without weight, not for people who need deep moisture.

The zero-conflict profile is a genuine practical advantage. Because this formula contains no actives that interact meaningfully with other skincare ingredients, it slots into any routine without restrictions. You can layer it under retinoids, vitamin C, niacinamide, AHAs, BHAs, or peptides without concern. For people with complex multi-step routines, having a hydration product that never causes problems is more valuable than it sounds.

Two honest limitations deserve mention. First, the potential fungal acne concern: Pseudoalteromonas ferment extract may feed Malassezia yeast in susceptible individuals. If you are prone to fungal acne, patch test carefully. Second, the scent: a minority of users detect a faint marine or seaweed note from the algae and bacterial extracts. Most people smell nothing, but if you are sensitive to ferment-derived odors, be aware.

At .20 for a product that lasts three to four months with twice-daily use, the financial risk of trying Marine Hyaluronics is negligible. It is a genuinely novel approach to a common skincare problem — the desire for hydration without texture — and for oily skin types, it may solve a problem that traditional HA serums created.