One simple supermarket ingredient that instantly transforms rice, seafood and fish for bolder flavor

It’s important to clarify this from the outset, because the name can be misleading. Seawater sold for culinary use should not be considered a refreshing beverage or an alternative to mineral water. It is a product intended for use in cooking, typically on its own or mixed with fresh water, depending on the dish and the desired saltiness.

The difference is significant. If someone tastes it straight, they’ll likely find it intensely salty and unpleasant. But that same concentration can make perfect sense when used in cooking: in a broth, a seafood rice dish, or a pot of seafood.

Although it may seem like a novelty at the supermarket, the idea of cooking with seawater isn’t just a modern whim. Many well-known chefs, such as Ferran Adrià, chef at El Bulli, and Ángel León, chef at Aponiente, have already explored this technique to enhance some of their culinary creations.

This doesn’t mean that buying a carton of seawater will turn an everyday rice dish into haute cuisine. But it does help explain why the product isn’t as absurd as it seems at first glance. When used properly, it follows a logic that’s very much a chef’s: using a salty, mineral-rich liquid to enhance the maritime character of certain dishes.

The main difference isn't that one is better than the other, but rather the type of salinity they provide. When we add table salt to water, we're mainly adding sodium chloride. It's a simple, inexpensive, and perfectly effective method for cooking pasta, vegetables, potatoes, or seafood.

Edible seawater, on the other hand, already has its own salinity and a more complex mineral composition. In cooking, this can result in a slightly more integrated flavor and a more pronounced marine nuance, especially in dishes where that flavor profile is appropriate: seafood, fish, rice dishes, fideuá, short-simmered broths, or potatoes intended for a seafood salad.

Simply put: salted water is used for salting; seawater, when used properly, can not only salt but also add more complex and profound nuances to dishes meant to taste of the sea.

But this ingredient has its pros and cons:

• Salted water allows for better control over the exact amount added, whereas
• seawater requires more caution: if used undiluted, it can be too salty, and if the liquid reduces during cooking, the salt becomes more concentrated. That’s why, at home, it’s usually wiser to mix it with fresh water and taste it before adding more salt.

The beauty of using seawater in cooking lies in how it seasons food: when you cook food in a liquid that’s already salty, the salt blends in during the cooking process rather than being added at the end. This can result in a more even saltiness.

It doesn’t replace a good fish stock or save a lackluster dish, but when used well, it can create a more rounded flavor, as if the saltiness were part of the dish itself rather than simply added on top.

It can be used in various dishes, but always in moderation: the goal isn’t to add more salt, but to bring out its mineral flavor.

• Seafood. This is its most obvious use. Cooking shrimp, prawns, mussels, spider crabs, or barnacles in a brine helps preserve the seafood’s natural flavor.
• Steamed fish and light broths. It can work well, but it’s best to mix it with fresh water and keep an eye on the reduction, since the salt becomes concentrated.
• Seafood rice dishes. It can replace part of the broth or water. It’s wise to taste before adding salt, since seafood, fish, canned goods, and stock also contribute salt.
• Potatoes for seafood salads. Boiling them with some seawater can give them more depth of flavor when combined with tuna, bonito, mussels, octopus, or fish.

When using it at home, it’s a good idea to keep three basic rules in mind:

• It’s better to use too little than too much: Except when cooking certain types of seafood, it’s usually safer to mix seawater with fresh water. As a guideline, one part seawater to two or three parts fresh water is a good starting point.
• Don’t add salt before tasting: If you’re using seawater, salt is already part of the recipe. Adding salt out of habit is the quickest way to ruin the dish.
• Be careful with reductions: During long cooking times, when making sauces, or when preparing concentrated broths, the water evaporates, but the salt remains. What initially seemed balanced can end up being too intense.

The temptation is understandable: if seawater is right there, for free, why buy bottled water? But it’s not the same thing. Seawater for food use is collected, filtered, tested, and bottled for culinary purposes; the water we collect on a beach doesn’t offer those guarantees.

Just because a beach is suitable for swimming doesn’t mean its water is safe for cooking. Those tests assess the safety of the water for swimming, not for consumption as an ingredient. Furthermore, near the shore there may be organic debris, localized pollution, hydrocarbons, microplastics, sand, decaying algae, or invisible contaminants.

Boiling it isn’t enough either: it may reduce some microbiological risks, but it doesn’t eliminate chemical contaminants or make the water safe. Therefore, it’s prudent to use bottled seawater intended for food use, not a bottle filled directly on the beach.

Using seawater in cooking is puzzling because we think of it as a beverage, when in reality it functions as an ingredient. It isn’t essential, nor does it turn an ordinary dish into haute cuisine, but when used well, it can add a more integrated saltiness and an interesting marine nuance.

The next time someone asks who drinks that, the answer will be simple: almost no one. But more than a few people might cook with it.