A matter of perspective?

From the port of Calais in France, on a good day you can see the white cliffs of Dover - some 20 miles away on the English coastline. The cliffs rise to about 100 metres above sea level and they appear as a thin strip of white rockface just above the horizon.

From my garden on Gabriola Island, most days I can see the Sunshine Coast on the BC mainland - also about 20 miles away across the Strait of Georgia. The difference here is that the mountains along the coastline make it seem so much closer - and I still find it difficult to believe that they really are 20 miles away. The difference, of course, is that the mountains in that part of BC rise to more than 1,400 metres - and therefore, despite the distance across the Strait, they are so much more prominent than the English coastline is from France.

Like the English Channel, the Strait of Georgia is crossed by numerous car ferries - with the route from Nanaimo to Tsawwassen passing close along the coastline of Gabriola, seemingly little more than a mile (but in reality probably two miles) from the shoreline near our house. A second ferry route from Nanaimo takes a more northerly route to Horseshoe Bay in West Vancouver - and from our window these ferries are also visible on the horizon, giving the impression that, as they pass through our field of vision, they are already close to the BC mainland.

In truth (as confirmed by the GPS tracking on the BC Ferries website) at the time that they are visible to us, these ferries are only half way across the Strait and probably still 10 miles from the distant BC coastline - so as they disappear from view they are not, as I had imagined, entering the approaches to Horseshoe Bay but merely disappearing over the horizon.

Erroneously, I had assumed that my view of the mainland took in the mountains and their lower slopes running right down to the coast. If that was the case, then I would be expect to be able to see the many cruise ships that pass along the BC coast en route from Vancouver to Alaska at this time of year - but I don't, as they are (I assume) also below my horizon.

From my vantage point on Gabriola, I am only about 25 metres above sea level. If I can't see the coastline of mainland BC, then where does my view of the Sunshine Coast actually start - 50 metres above sea level? 100 metres? 200 metres?

Now, if only I had become a scientist......