According to Ourhollowearth.com you will find the Arctic hole at 84.4 N Latitude, 141 E Longitude. 
Another site says of this location,"Recent Satellite photos show darkened open seas, which leads me to believe that there is a drop in the elevation /sea level in this region. Additionally, infrared photos reflect a hot-spot. This region is supposed to be nothing but ice." The claim I've seen is that the hole is 1400 miles across. As you can see, 1400 miles is almost the entire distance from the top of Greenland to the New Siberian Islands. Compare this to the satellite photo below looking down on the Arctic Circle.
Having trouble visualizing this? Me too! What would a north hole 1,400 miles across look like? 1,400 miles is greater than the distance from Sacramento CA to Amarillo TX! The thing is, on the open sea with no land around, (or on flat land) one can normally see only about 12 miles in any direction due to the curve of the earth. In other words, as you moved into the gradual depression of the opening, it is true that you wouldn't know it at first. Once you were far enough in, however, you SHOULD see a huge and disturbing sight: the horizon looming too high in the sky. In fact, some say such a vision has been reported in the the northern Arctic. The hillingar effect or arctic mirage, however, is credited as an optical illusion.
The Moon's average distance from the Earth is 238,328 miles and we can certainly see that. We'd be able to see something 1400 miles distant. But what would it look like?
To help you visualize, consider this. Typical shuttle flights range at around altitudes about 300 km (186 miles above the earth). Here is a photo showing the curve of the earth from shuttle height.
At 186 miles up, one is already in space, so the sky becomes black. The horizon would be 1,333.75 miles from the observer. (186 miles = 982,080 feet high, 1.17 times the square root of your eye height = Distance to the horizon in nautical miles. 1 nautical mile = 1.15078 miles. 15)
In the above photo (assuming my calculation is correct, and the 
shuttle was 186 miles high when the photo was taken) the horizon doesn't show much detail. In other words, what you might see if you were into the hole would be something like this:
This is a composite photo I created using a space shuttle photo (STS095-719-45.jpg) and a photo by Thomas Seiler. As you can see, The other side of the hole is so far away that the land just looks like a strange sky illusion. When you look between the twin peaks, you are seeking across the hole to land that is an estimated 800 miles away. As you look up to the horizon, the edge of the hole is 1,333 miles away. That's the best I can do right now to visualize what this would really look like if the whole hole story were true.
Why have reasonable persons considered that the earth might be hollow? Here are a few: There are stories dating back thousands of years that speak of an Underworld. Some known anomalies, it is claimed, may be explained by the hollow earth theory: freshwater icebergs, whole frozen woolly mammoths with tropical vegetation still undigested in their stomachs, a magnetic ring instead of a point for the north pole, the above photos, animals migrating north for the winter in Greenland, and statements heard by millions of people about a historic journey of Admiral Richard Evelyn Byrd in 1947 to a land beyond the North Pole.
