What's the largest island you can drive to from the mainland?

Factual Questions
1

What’s the largest island you can drive to from the mainland?

Just got to wondering. After a small bit of research, I decided to break it into three sub-questions based on whether you can drive via a bridge, a causeway, or a tunnel. Of course, some islands may have multiple ways to drive to and those may involve more than one of those modes. Let’s say that if you can get there via a tunnel, that has to be the only way to get there. If there’s also a bridge route, it counts in the bridge category. Ditto for causeway. Ignore ferries for this question.

So far, I have Cape Bretton Island (area 10,311 sq km) as the largest via a causeway and Zealand, Denmark (area 7,031 sq km) as the largest via bridge. I have no good answer for tunnel.

ETA: Railway bridges/tunnels also don’t count, just in case anyone was wondering.

2

You can travel to Great Britain via tunnel from the mainland, although you can’t drive. You can take your car on the train, though.

Sicily is larger than Cape Bretton Island. They’re about to start construction of a road bridge linking it to the mainland. There’s also a proposal to link Sicily to Tunisia by tunnel, but I wouldn’t hold my breath for that one.

3

Copenhagen was the obvious one for me as well but the OP covered it.

If they ever get round to building it the Messina Bridge will allow you to drive to Sicily.

ETA, didn’t see your comment @UDS1, you mentioned that bridge as well

4

If they build the tunnel, you won’t have to hold your breath to get from Sicily to Tunisia.

5

It’s awfully hard to find an island that is only connected to the mainland by tunnel. I’ll open the bidding with Hitra, Norway, with an area of 571.5 km2. Obviously this is much smaller than the others, and I expect that my fellow Dopers will be able to improve on it.

6

I’ll throw in Long Island, NY at 1,401 mi² and Prince Edward Island at 2,185 mi²

Also Honshu, Japan at 87,992 sq miles, though it is the largest island there, so I’m not sure the OP counts it.

7

How about Key Largo? I know it’s relatively small, but it’s way out there.

8

Also, I’m assuming that by “the mainland” the OP means “the large contiguous land masses of Eurasia, Africa, the Americas, or Australia.” Otherwise there might be some options in Japan that I’ve missed.

9

Also how does one define the difference between a causeway and a bridge? Most causeways I know of appear to be just a very long bridge low to the water.

10

Long Island has multiple connections to the mainland and is 2,255 sq-km.

I would think that is the biggest in North America.

Vancouver Island is even bigger at 19,946 sq-km. but I don’t think you can drive there.

11

I was thinking Long Island, too, but the aforementioned Cape Breton Island in Nova Scotia is 10,000+sqkm and is connected to the mainland by a causeway.

12

I suppose it’s just that boats can pass under a bridge. Although that’s just reframing the question of “how high” to “how large a boat”.

13

One answer to the OP is Greenland - for several months each year it’s theoretically possibly to drive there over the frozen sea, from Canada. But of course there are no roads, and it’s not via tunnel, bridge, or causeway. I wonder if anyone has ever attempted it? The British car show Top Gear drove to the North Pole several years ago, using a modified Toyota Hilux pickup and an extensive support team. I can’t remember if they started from solid land, or took a boat to get to the edge of the ice cap.

14

Possibly only 2 by road, depending on how ‘connection to the mainland’ is defined by the OP, which looking it up the word multiple would mean more than 2. Throgs Neck, Whitestone bridges. All other road connections don’t go to the mainland but other islands (Staten, Manhattan, Randels, Rosevelt, along with various ones to barrier reef islands, bay/channel islands and the like). There is also one rail bridge connection to the mainland also (Hell Gate).

15

I’ll throw in a vote for Rhode Island.
3,144 square kilometers

16

Thank you. Being the world’s only island not completely surrounded by water gives us an advantage.

17

I get 1954 square kilometers.

18

We use square miles here, and there are 1545 of them altogether, but about 1/3 of that is Narraganset Bay.

19

Well…the Rhode Island government says:

Rhode Island is the smallest state in size in the United States. It covers an area of 1,214 square miles. - SOURCE

I’ll leave the conversion math to others.

20

Yeah, but lots of bits of the state of Rhode Island are NOT island. In fact, most of it isn’t an island. The largest island in the state is Aquidneck island, with 37.8 square miles.