Giant kelp plant
Giant kelp is a large brown alga that grows from the seafloor and can form dense underwater forests.
Also known as: giant kelp, Macrocystis pyrifera
How big is it?
30 m long
Also 98.43 ft
Representative full thallus length · representative
Typical recorded range: 20 m to 45 m.
A little perspective
About 3 times the approximate aircraft length of Human-powered aircraft.
Human-powered aircraft: A human-powered aircraft is a lightweight aeroplane propelled solely by the pilot using pedals to drive a propeller.
Measurements, assumptions & sources +
Giant kelp plant
A representative mature giant kelp (Macrocystis pyrifera) thallus 30 m from holdfast to longest blade tip. Flexible fronds change shape with current, and a real holdfast anchors to rock rather than forming roots.
NOAA Ocean Service — Kelp forests
The marked representative full thallus length is calibrated. Unmeasured illustration details are representative.
Human-powered aircraft
A Gossamer Albatross-style human-powered aircraft with NASA's quoted 94 ft (28.7 m) span, approximately 10 m length, 32 kg empty mass and a representative 5 m/s flight speed. The pilot is excluded from empty mass.
The marked approximate aircraft length is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 30 m
For comparison, this page uses representative full thallus length. This is labelled representative; the central value is useful for comparison, while real values or measurement solutions can vary. The recorded range is 20 m to 45 m.
A representative mature giant kelp (Macrocystis pyrifera) thallus 30 m from holdfast to longest blade tip. Flexible fronds change shape with current, and a real holdfast anchors to rock rather than forming roots.
The marked vertical span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
Giant kelp plant dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 30 m | 20 m to 45 m | representative |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
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Around the same scale · TransportHarbour tugboat30 mA harbour tugboat is a powerful, manoeuvrable vessel designed to assist larger ships with docking and navigation in confined waters.
Nearest higher value · Living thingsSiphonophore colony40 mA siphonophore is a floating colony of specialised animals called zooids that function together as one organism-like body.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- NOAA Ocean Service — Kelp forestsGiant-kelp biology and tens-of-metres growth scale; the atlas uses a representative mature thallus.
There’s always another scale
Follow your curiosity.
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TransportHuman-powered aircraft28.7 mA human-powered aircraft is a lightweight aeroplane propelled solely by the pilot using pedals to drive a propeller.
SpaceRosetta spacecraft32 mRosetta was an ESA spacecraft launched to study comet 67P/Churyumov–Gerasimenko, carrying the Philae lander and powered by solar arrays.
SportDoubles tennis court23.77 mA doubles tennis court is the marked playing surface used for tennis with the outer doubles sidelines included.Living thingsBlue whale25 mA blue whale is a baleen whale that feeds by filtering small animals from seawater.
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TransportLockheed SR-71 Blackbird32.7 mThe Lockheed SR-71 Blackbird is a long-range, high-altitude reconnaissance aircraft developed for the United States Air Force during the Cold War.