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.

Formula

The Science

The hydrating mechanism in Marine Hyaluronics relies on exopolysaccharides — polysaccharides secreted by Pseudoalteromonas bacteria as a survival adaptation to extreme marine environments. These organisms produce carbohydrate-based polymers that form hydrated biofilms, protecting the bacteria from osmotic stress and temperature fluctuations. When applied to human skin, these exopolysaccharides create an ultrathin moisture-binding layer that functions analogously to hyaluronic acid's water-holding capacity but with a fundamentally different molecular architecture.

Ahnfeltia concinna, the Hawaiian red algae in this formula, contributes agar-like polysaccharides that form a gel matrix capable of holding water. While the specific cosmetic research on this species is limited, the broader class of red algae polysaccharides (including carrageenan and agar) are well-documented moisture-retention agents in both food science and cosmetic formulation.

The eleven amino acids in this formula replicate components of the skin's Natural Moisturizing Factor — a complex of hygroscopic molecules that the stratum corneum produces to maintain hydration. NMF components including amino acids, PCA, sodium PCA, and sodium lactate have been extensively studied in dermatological literature. Research consistently shows that NMF levels decline with age and environmental stress, and that topical application of NMF-mimicking compounds can measurably improve stratum corneum hydration and barrier function.

It is worth noting that the evidence base for the specific marine ingredients in this formula is more limited than for established humectants like glycerin and hyaluronic acid. The efficacy of Pseudoalteromonas exopolysaccharides in cosmetic hydration is supported primarily by manufacturer data and in vitro studies rather than extensive independent clinical trials. The product's practical performance — demonstrated by its high user ratings and large review volume — provides real-world validation, but consumers seeking the most rigorously evidence-backed hydration should be aware of this distinction.

Dermatologist Perspective

Dermatologists generally view Marine Hyaluronics as a reasonable lightweight hydration option for oily and combination skin types, though they note that the evidence base for the marine-derived ingredients is less robust than for established humectants like glycerin, hyaluronic acid, and ceramides. Board-certified dermatologists recommend this product primarily as a layering aid — a lightweight first serum that provides baseline hydration and improves the absorption of subsequent treatments. For patients with oily skin who avoid hydrating serums due to textural complaints, dermatologists note that this product removes the most common barrier to proper hydration. The NMF-supporting amino acid complex is well-understood in dermatological science and adds legitimate hydration value beyond the marine ingredients alone.

Guidance

DECIEM created Marine Hyaluronics in 2018 to offer a hydration solution for people who found their existing Hyaluronic Acid 2% + B5 too sticky, heavy, or prone to pilling. Rather than reformulating with lighter HA, they went in an entirely different direction — sourcing hydrating compounds from marine bacteria and Hawaiian algae that mimic HA's water-binding properties without its texture. The name is deliberately provocative: it promises the benefits of hyaluronic acid while delivering them through a fundamentally different ingredient approach.

About The Ordinary Established Brand (5–20 years)

The Ordinary launched under DECIEM in 2016 and rapidly became the most disruptive force in skincare by offering clinical-grade actives at unprecedented price points. Now owned by Estée Lauder Companies, the brand has built nearly a decade of consumer trust through ingredient transparency and accessible pricing.

Brand founded: 2016 · Product launched: 2018

Myth vs. Reality

Myth

Marine Hyaluronics contains hyaluronic acid from marine sources

Reality

This product contains zero hyaluronic acid. The "Hyaluronics" in the name refers to the hyaluronic acid-like hydrating function of the marine-derived ingredients, not to HA itself. The actives — Pseudoalteromonas exopolysaccharides, Pseudoalteromonas ferment extract, and Ahnfeltia concinna extract — are polysaccharides and glycoproteins that bind water similarly to HA but with a completely different molecular structure and a much lighter feel.

Myth

If it feels like water, it cannot be providing real hydration

Reality

The marine exopolysaccharides form a microscopic hydrating film that is too thin to feel but still binds water effectively. Glycerin, the amino acid complex, sodium PCA, and sodium lactate — all established NMF components — provide additional hydration through mechanisms independent of texture. Viscosity is not a measure of hydration efficacy.

FAQ

Common Praise

"Ultra-lightweight water-like texture absorbs instantly with zero tackiness"

"Excellent hydration layer for oily and acne-prone skin without heaviness"

"Layers beautifully under any product without pilling or interference"

"Affordable at .20 for a unique marine-derived hydrating serum"

"No conflicts with other actives — fits into any routine"

Common Complaints

"Some users detect a faint fishy or seaweed odor from the marine extracts"

"Hydration feels short-lived — insufficient as a standalone for very dry skin"

"Water-thin consistency is difficult to control from the dropper"

"Some users feel it does nothing noticeable and is essentially expensive water"

"Potential fungal acne trigger due to ferment extract"

Appears In

best serum for oily skin best lightweight hydrating serum best the ordinary products best serum for summer best hydrating serum under 10

Related Conditions

dehydration oiliness dullness

Related Ingredients

hyaluronic acid glycerin sodium pca