Why does 'alga' use 'el' instead of 'la'?

Spanish feminine nouns that begin with a stressed 'a' or 'ha' take the masculine article 'el' in the singular to avoid an awkward double-a sound: 'el alga,' 'el agua,' 'el águila.' The noun remains feminine — adjectives still agree in feminine form ('el alga verde,' not 'el alga verde' with masculine adjective) — and the plural reverts to 'las': 'las algas.'

'Sargazo' is the Spanish word for sargassum, a type of brown floating seaweed common in the Atlantic Ocean and Caribbean Sea. It has become a well-known term in Mexico and the Caribbean due to large sargassum arrivals on beaches. The Sargasso Sea ('Mar de los Sargazos') is named after this seaweed.

How do you say 'kelp' in Spanish?

Kelp is generally translated as 'quelpo' or 'kelp' (borrowed directly from English) in scientific contexts. More commonly, people say 'alga kelp' or simply 'algas gigantes' (giant seaweed). In Chile, the edible kelp known as cochayuyo has its own name from Mapuche: 'cochayuyo.'

Spanish vocabulary · Beginner

How to Say Seaweed in Spanish: Alga

Written by Sofia Ramirez, Lead Spanish Curriculum Editor · Reviewed May 2026

Alga / Algas · noun · AHL-gah (singular) / AHL-gahs (plural)

The Spanish word for 'seaweed' is 'alga' (el alga in singular, las algas in plural). Despite being a feminine noun, 'alga' takes the masculine article 'el' in the singular because it begins with a stressed 'a' — this is a phonetic rule shared by words like 'el agua' and 'el águila.' In the plural, the regular feminine article returns: 'las algas.' The term 'alga marina' specifies marine seaweed as opposed to freshwater algae. In the Caribbean and Mexico, 'sargazo' refers specifically to sargassum, the floating brown seaweed that washes ashore on beaches.

'Alga' is pronounced AHL-gah, with two syllables and stress on the first. The 'g' before 'a' is a hard 'g' like in 'go.' The plural 'algas' is AHL-gahs. 'Sargazo' is pronounced sar-GAH-soh.

Las algas marinas son ricas en minerales y vitaminas.

Seaweed is rich in minerals and vitamins.

Seaweed in Spanish: Quick Reference

Below are the most common Spanish words for seaweed, with pronunciation and regional usage notes.

Spanish	English	Pronunciation	Region / Register
alga / algas	seaweed	AHL-gah (singular) / AHL-gahs (plural)	Default, widely understood
alga marina	seaweed		sea-specific algae, universal
sargazo	seaweed		sargassum seaweed, Caribbean and Mexico

How Native Speakers Use Alga / Algas

Real example sentences across three contexts you'll actually run into.

At a sushi restaurant

El sushi está envuelto en una lámina de alga nori.

The sushi is wrapped in a sheet of nori seaweed.

'Alga nori' is how Japanese nori seaweed is referred to in Spanish. 'Lámina de alga' (seaweed sheet) is the natural phrasing for the wrapper.

At the beach

La playa estaba llena de algas después de la tormenta.

The beach was full of seaweed after the storm.

The plural 'algas' is more common in everyday speech since seaweed usually appears in masses. Note the feminine plural article 'las' returns in the plural.

Health and nutrition

Incorporé algas marinas a mi dieta por sus beneficios nutricionales.

I added seaweed to my diet for its nutritional benefits.

'Algas marinas' is the full term for marine seaweed, distinguishing it from freshwater algae. It is common in health food and nutrition contexts.

Avoid These Mistakes When Using Alga / Algas

Using the feminine article in singular

Incorrect: La alga marina se usa en la cocina japonesa.

Correct: El alga marina se usa en la cocina japonesa.

Even though 'alga' is feminine, it takes the masculine article 'el' in the singular because it begins with a stressed 'a.' This avoids the awkward vowel clash of 'la alga.' In the plural, use 'las algas' normally.

Inventing a word like 'hierba marina'

Incorrect: Comimos hierba marina en el restaurante.

Correct: Comimos algas en el restaurante.

While 'hierba marina' might seem like a logical calque of 'seaweed' (sea + weed), it is not the standard term and could be misunderstood. The correct word is 'alga' or 'algas.' 'Hierba' refers to land herbs or grass.

Lock in Seaweed Vocabulary with the Parrot Method

Why word lists alone don't stick

Memorizing a translation feels productive, but most learners forget 70% of what they studied within 48 hours. Vocabulary needs spaced repetition AND real-world exposure to transfer to long-term memory.

See Alga / Algas used by native speakers

Parrot's short-form videos feature native speakers using alga / algas in real situations. Context-based exposure beats flashcards, you hear Las algas marinas son ricas en minerales y vitaminas. while watching someone live the moment, connecting meaning, sound, and rhythm at once.

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Common Questions About Seaweed in Spanish

Why does 'alga' use 'el' instead of 'la'?: Spanish feminine nouns that begin with a stressed 'a' or 'ha' take the masculine article 'el' in the singular to avoid an awkward double-a sound: 'el alga,' 'el agua,' 'el águila.' The noun remains feminine — adjectives still agree in feminine form ('el alga verde,' not 'el alga verde' with masculine adjective) — and the plural reverts to 'las': 'las algas.'
What is 'sargazo'?: 'Sargazo' is the Spanish word for sargassum, a type of brown floating seaweed common in the Atlantic Ocean and Caribbean Sea. It has become a well-known term in Mexico and the Caribbean due to large sargassum arrivals on beaches. The Sargasso Sea ('Mar de los Sargazos') is named after this seaweed.
How do you say 'kelp' in Spanish?: Kelp is generally translated as 'quelpo' or 'kelp' (borrowed directly from English) in scientific contexts. More commonly, people say 'alga kelp' or simply 'algas gigantes' (giant seaweed). In Chile, the edible kelp known as cochayuyo has its own name from Mapuche: 'cochayuyo.'