Idaho and Bay of Biscay are almost exactly the same size

Idaho (state) covers about 216,000 km² (83,500 mi²) and the Bay of Biscay (bay) about 216,000 km² (83,400 mi²). Their outlines are laid over each other below at one scale. The Bay of Biscay outline is Natural Earth’s, checked against the published area.

216,000km²Idaho
216,000km²Bay of Biscay

200 km

Idaho
Bay of Biscay

What fits

Bay of Biscay is 100% of the size of Idaho.
The measured areas differ by 185 km², less than half a percent: closer than the measurement itself is certain.
Measured in Belgiums: Idaho is about 7.05, Bay of Biscay about 7.05.

How they differ

Their centres are about 7,900 km apart.
On a standard web map Bay of Biscay looks larger than Idaho: Idaho at 44°N is drawn about 2.0× too large and Bay of Biscay at 46°N about 2.0×, so the map shows Bay of Biscay as 1.04× the size of Idaho, when Idaho is 1.00× the size of Bay of Biscay.
Together Idaho and Bay of Biscay cover 432,000 km², close to the size of Iraq (437,000 km², 1.2% bigger).
Bay of Biscay's centre is 1.2° of latitude, about 130 km, farther north than Idaho's.
Idaho is a state of the United States; it is not drawn with its waters removed, and its measured area is the Natural Earth outline's.
The Bay of Biscay is a bay and ranks 25th of the 42 seas on sizeversus by area.
Laid out flat, Idaho stretches about 777 km north to south and 500 km east to west; the Bay of Biscay about 571 km by 592 km.
Poured over Idaho, the 389,000 km³ that Wikidata records for the Bay of Biscay would stand 1,799 m deep.
Our measured 216,000 km² is 3.1% below Wikidata’s published figure of 223,000 km². Published areas of lakes and seas move with the water level and with what is counted, so a few percent is expected.

Who wins on what

Measure	Winner	By
Larger area	Idaho	1.00×
Farther north	Bay of Biscay	1.2° of latitude

Both against the same yardsticks

Yardstick	Idaho	Bay of Biscay
Belgium 30,700 km²	7.05×	7.05×
United Kingdom 244,000 km²	0.89×	0.89×
Germany 358,000 km²	0.60×	0.60×
Japan 374,000 km²	0.58×	0.58×
France 548,000 km²	0.39×	0.39×
India 3,151,000 km²	0.07×	0.07×
Brazil 8,473,000 km²	0.03×	0.03×
United States 9,447,000 km²	0.02×	0.02×
Russia 16,980,000 km²	0.01×	0.01×

Each figure is the place's area divided by the yardstick's.

Side by side

	Idaho	Bay of Biscay
Is a	StateUnited States	Baysea on sizeversus
Area, measured	216,000 km²83,500 mi²	216,000 km²83,400 mi²
Area, published	217,000 km²Wikidata	223,000 km²Wikidata
Rank by area	–	25th of 42seas
Greatest depth	–	4,735 mWikidata
Volume	–	389,000 km³
Latitude range	42°N to 49°N	43°N to 48°N
On the shore	–	2 on the shore

Published figures: Wikidata (CC0). A lake or a sea has no legal boundary: the measured area is that of Natural Earth’s outline, and it is shown beside the published one.

Natural Earth’s outlines of France and Spain lie within 25 km of the outline of the Bay of Biscay. That is what its geometry says, and it is not a statement about who owns the water or where any border runs in it.

Similar in size to Idaho

Similar in size to Bay of Biscay

More comparisons

Sources and method

Outlines: Lakes and seas: Natural Earth 1:10m physical vectors (public domain), kept only where the measured area is within 10% of the published one. Countries and regions: Natural Earth, 1:10m Admin 0 and Admin 1, public domain.
Boundary: De facto, as drawn by Natural Earth. A lake or a sea has no legal boundary of its own; the outline is a cartographic one.
Area: Measured on the WGS84 ellipsoid from the full-detail outlines, shown rounded. The published figure comes from Wikidata (CC0), fetched 2026-11-11, and is shown beside the measured one.
Drawing: Each outline is projected with an equal-area projection centred on its own centroid, so areas stay true and the two can be laid over each other.
Data built: 2026-11-11

Full method