The monument of nature "Dense Island is located in the Vyborg district, 2 km on West from the city of Vysotsk, 7 km from Vyborg to the South-West.
"The island is Densely organized as regional geological natural monument in 1976. Its area is 54 hectares. The purpose of creation of a monument of nature – the preservation of the original forms of relief: "mutton foreheads" and unique granite-rapakivi to the surface. Protected objects on the territory of the Island is Dense" is a relief "mutton foreheads" and granite-rapakivi.

"Mutton foreheads" are smoothed by the movement of the glacier the rocks that are composed of bedrock protruding to the surface. Particularly smooth and gentle are the slopes that were oriented to the direction of movement of the glacier, the slopes on the other hand often steep and uneven. The small group of "mutton foreheads" is also called curly cliffs. Mutton foreheads meet in mainland and mountainous zones of the ancient and modern glaciation. "Mutton foreheads" are particularly common in the Baltic shield.

Granite-rapakivi (translated from Finnish "rotten, crumbling stone") is a type of granite rock with an acidic composition. Granite-rapakivi consists of 40% of orthoclase, 30% of idiomorphic quartz, 20 % of oligoclase. also contains a small amount of impurities minor accessory minerals (2 %), such as amphibole, orthite, diopside, sphene, Apatite, magnetite, etc. On the cut rapakivi clearly visible large grain size of this granite. The level of durability it is much inferior to the samples of fine-grained granite. This type of granite can be painted in different shades of brownish-pink color, sometimes greenish, reddish and black rapakivi. In addition to the Leningrad region and Karelia granite-rapakivi widely spoken in Finland, Sweden, Ukraine (Cherkasy region). By the way, the Alexander column and the monolith under the "bronze horseman" – from this stone.

The territory of the nature monument "Dense Island" is promising for eco-tourism as a separate object, as well as for the organization of tourist routes in protected natural monuments of the Gulf of Finland and the Karelian isthmus.

The island is Dense in plan has the shape of a horseshoe. The North-Western part of the island is a granite rock with a height of about 30 m, which stretches for half a kilometer and smoothed by glacier gentle slope "mutton foreheads". The East coast is Thick – steep (height of the cliff is about 20 m). This is due to the tectonic fault. In other parts of the island is Dense, you can find polished rocks. On the surface clearly stand out large ovoids – edged crystals of mica and quartz rounded crystals of feldspar, which are typical of granite-rapakivi.

In the Dense center of the island juts out picturesque Bay is the favorite place of Parking of the boaters. Water spaces and the many wooded Islands with cliffs, rugged coastlines, "mutton foreheads", long and narrow bays, – all this forms a picturesque landscape of the archipelago, which separates the Northern coast of Scandinavia and not typical for other areas of the Leningrad region.

On the territory of the natural monument is prohibited to develop and produce granite, make a fire.