Step 1: Compare places
Use a map or two contrasting ecoregions so students can see that one ocean contains very different regions and features.
Ocean Literacy Principle 1
Earth has one big ocean with many features
The ocean is one connected global system, even though it includes very different regions, coastlines, currents, habitats, and seafloor features. This principle helps students connect geography, movement, and ecosystems.
Guiding question: How can very different ocean places still belong to one connected system?
What this principle means
One connected ocean
Named oceans help us describe the planet, but they are all part of one connected body of water.
The ocean is one connected body of water.
The ocean covers about 70% of Earth. Even though we divide it into the Atlantic, Pacific, Indian, Southern, and Arctic, it is still one connected global ocean.
Ocean resources are vast but limited.
The ocean is immense, but its living systems, chemistry, and materials are not endless. Human use and management matter.
Many features and regions
The global ocean contains very different kinds of places, from deep basins to coastlines and estuaries.
Ocean basins include major seafloor features.
Ocean basins contain underwater mountains, valleys, ridges, shelves, and deep trenches. These features form as Earth’s crust moves, and some of Earth’s highest and lowest places are found in the ocean.
Sea level changes over time.
Sea level is the average height of the ocean. It changes when land rises or sinks, when ice melts or grows, and when seawater warms or cools.
Most of Earth’s water is in the ocean.
Seawater is salty and has distinctive physical and chemical properties. Ocean chemistry, including pH, is important for marine life and for Earth’s climate system.
Movement connects everything
Ocean movement links distant places by transporting water, heat, nutrients, organisms, sediments, and pollutants.
Ocean water is always moving.
The ocean circulates through a global system driven by wind, tides, and Earth’s rotation. This movement spreads heat, nutrients, and life, and shapes marine ecosystems and climate.
The ocean is part of the water cycle.
Water moves between ocean, land, and atmosphere through evaporation, condensation, precipitation, runoff, and groundwater flow.
Water from land flows into the ocean.
Rivers and streams carry freshwater, sediments, nutrients, and pollutants from land to sea, linking terrestrial and marine systems.
Key ideas
- The ocean is one connected body of water.
- Ocean basins contain major seafloor features.
- Ocean water is always moving.
- Sea level changes over time.
- Most of Earth’s water is in the ocean.
- Ocean chemistry matters.
- The ocean is part of the water cycle.
- Water from land flows into the ocean.
- Ocean resources are vast but limited.
Teach this principle
Step 2: Identify connections
Add a mobile species or a current-driven process to show that these places are linked rather than isolated.
Step 3: Think in systems
Ask students what moves between places, such as heat, water, nutrients, organisms, sediments, or pollutants.
Why this matters
This principle gives students an early introduction to systems thinking by showing that different places and features still belong to one connected ocean. It is foundational because later ideas about biodiversity, climate, migration, and human impact all depend on understanding connection.
What students should take away
Students should come away understanding that the ocean is not a set of isolated facts or separate places. It is one global system made of many distinct regions that are linked by movement, exchange, and change.
Classroom prompt: If two ocean regions look very different, what evidence shows that they still belong to one connected system?
Teach with Blue Biome
Explore this principle with the platform
WebGIS
Compare ocean basins, regions, seafloor features, and currents to see how different places fit into one global ocean.
Knowledge Graph
Trace how species, places, processes, threats, and opportunities are connected across the system.
Cards
Use cards to explore examples of movement, connection, and large-scale ocean processes.
Start here
Species
Follow a species across the system
Use swordfish to explore how one organism connects distant ocean regions.
Ecoregion
Compare two regions
Compare one highly productive region with a contrasting basin or gyre to highlight both difference and connection.
Opportunity
Explore a current or process
Use deep currents to discuss what moves through the ocean and how distant places influence one another.
Featured examples
Featured Species
Species
Swordfish
Swordfish help explain the principle because they move through large parts of the ocean system rather than staying inside one neat region.
Species
Tiger shark
Tiger sharks show that wide-ranging predators depend on connections among coastal habitats, open water, and large-scale ocean movement.
Species
Copepod
Copepods help explain the principle because even very small drifting organisms are carried and distributed by connected ocean waters.
Featured Ecoregions
Ecoregion
Equatorial Pacific
Distinctive: This region is shaped by strong equatorial circulation and productive waters.
Connected to the global system: It is connected to the global system through currents, climate processes, and heat transport.
Ecoregion
Mediterranean Sea
Distinctive: This is a semi-enclosed sea with distinct coastlines, water exchange, and human influence.
Connected to the global system: It still belongs to the connected ocean system because it exchanges water, heat, and organisms with the wider Atlantic.
Ecoregion
Indian Ocean Gyre
Distinctive: This region is defined by large rotating current systems across the open ocean.
Connected to the global system: It shows how movement links distant waters and redistributes heat, nutrients, and marine life.
Featured Cards
Opportunity
Deep Currents
Deep Currents illustrate the principle by showing how water movement links distant parts of the ocean below the surface.
Special
Turning Tide
Turning Tide illustrates the principle by showing that changes in movement and conditions can shift connections across the larger ocean system.