seabed

seabed — noun

1. the layer of rock, sand, or mud that forms the bottom of an ocean or sea

1.nounB1
Definition

the layer of rock, sand, or mud that forms the bottom of an ocean or sea

Example

The research vessel dropped a camera to film the seabed three kilometres below.

collocation: drop + to the seabed

Adina studied photographs of the seabed taken near a deep-ocean volcano.

collocation: photographs of the seabed

Common collocations
  • on the seabed
  • the seabed + mining / exploration / mapping
  • lie / rest / sit on the seabed
  • drop / lower something to the seabed
  • seabed sediment / rock / terrain
  • map / survey the seabed
Synonyms
  • seafloor

    the exact same meaning; preferred in scientific and technical writing

  • ocean floor

    equally common in general English; slightly less technical than seafloor

  • ocean bottom

    more general and informal; can also refer to the bottom of a large lake

Grammar Patterns

the seabed

on the seabed

Usage Note

Seabed is almost always used with the definite article the. In everyday conversation, ocean floor or sea floor are more common alternatives. This word appears frequently in news reports about underwater cables, deep-sea mining, and marine archaeology.

Common Mistakes

❗ ‘The divers explored the seabed of Lake Geneva.’ ✅ ‘The divers explored the bottom of Lake Geneva.’ — Seabed refers only to the floor of an ocean or sea, not a lake.

❗ ‘The children played on the seabed at the beach.’ ✅ ‘The children played on the beach.’ — Seabed describes the deep ocean floor, not the sandy shore beside the water.

Word family

  • seafloor
    nounB2

Synonym discussion

Sense: noun/1

Seabed, seafloor, ocean floor, and ocean bottom all describe the same physical feature: the surface at the bottom of an ocean or sea. Seabed is the most common general-purpose term, used in news articles, documentaries, and everyday English. Seafloor sounds more technical and is preferred in scientific papers, oceanography textbooks, and academic discussions of plate tectonics or marine geology. Ocean floor is interchangeable with seabed in most contexts but feels slightly more informal and is often used in travel writing and nature documentaries. Ocean bottom is the most general and least specific; it can also refer to the bottom of a large lake, whereas seabed and seafloor strictly refer to saltwater bodies. For example: “The submarine mapped the seabed near the trench” sounds natural in a news report; “The team analysed seafloor sediment samples” fits a journal article; and “Creatures of the ocean floor” works well as a documentary title.

seabed ↗seafloorocean floorocean bottom

Common collocations

Nouns

  • seabed mining
  • seabed exploration
  • seabed mapping
  • seabed sediment
  • seabed terrain

Phrases

  • lie on the seabed
  • drop to the seabed
  • map the seabed
  • drill into the seabed
  • rest on the seabed

Prepositions

  • on the seabed
  • across the seabed
  • below the seabed
  • near the seabed

Etymology

Old EnglishMiddle EnglishEnglish

Seabed is a compound of sea (from Old English sæ, meaning a large body of salt water) and bed (from Old English bedd, meaning a bottom or resting place). The word has been used since the 16th century to describe the ground beneath an ocean or sea, drawing on the metaphor of the sea ‘lying down’ on the floor beneath it.