what is the meaning behind wanderer above sea of fog
The painting is composed of various elements from the Elbe Sandstone Mountains in Saxony and Bohemia, sketched in the field but in accordance with his usual practice, rearranged by Friedrich himself in the studio for the painting. In the background to the right is the Zirkelstein. The mountain in the background to the left could be either the Rosenberg or the Kaltenberg. The group of rocks in front of it represent the Gamrig near Rathen. The rocks on which the traveler stands are a group on the Kaiserkrone. 
Wanderer above the Sea of Fog is true to the Romantic style and Friedrich’s style in particular,  being similar to other works such as Chalk Cliffs on Rügen and The Sea of Ice. Gorra’s (2004) analysis was that the message conveyed by the painting is one of Kantian self-reflection, expressed through the wanderer’s gazings into the murkiness of the sea of fog.  Dembo (2001) sympathised, asserting that Wanderer presents a metaphor for the unknown future.  Gaddis (2004) felt that the impression the wanderer’s position atop the precipice and before the twisted outlook leaves “is contradictory, suggesting at once mastery over a landscape and the insignificance of the individual within it”. 
Friedrich’s landscapes are nearly always large; they are often sombre or portentous. The people in them are frequently on the verge of things, the edge of a sea, the edge of a valley, a predicament that gives rise to the suggestion of journeys being made. Yet these are as much existential journeys — journeys of contemplation — as they are physical ones. Friedrich’s more tangible symbol of travel, the sailing boat, is usually shown in the middle or far distance. These vessels become another transitory element, coming and going like the sunlight, for the gazing people to peer at and silently yearn for.
The success of this painting, I think, lies in the possibility of this ambiguity: that a scene of such glory can also pose the threat of tragedy or personal alienation. What is he thinking as he stands there? It is impossible to tell.
Caspar David Friedrich’s On the Sailing Boat features the bow of a ship heading towards the horizon. Two figures, a man in a blue suit and hat and a woman in a pink dress with white lace collar, hold hands while looking at what lays ahead. The right side of the canvas is consumed by a closely focused depiction of the sail and the boat’s mast. In the distance, the viewer can discern the faint outline of buildings, silhouetted in mist. The largest expanse of the canvas is occupied by a glowing yellow sky.
This painting, one of his earliest, embodies many of the Romantic motifs and themes he would address throughout his career, most notably the important symbolism of the landscape itself. Indeed, although the altarpiece includes a crucifix, the emphasis is placed on the spiritual essence of nature. He described the work: “High up on the summit stands the cross, surrounded by evergreen fir trees, and evergreen ivy twines about the base of the cross. The glowing sun is sinking, and the Saviour on the cross shines in the crimson of the sunset . The cross stands on a rock, as unshakably firm as our faith in Jesus Christ. Fir trees rise around the cross, evergreen and everlasting, like the hope of men in Him, the crucified Christ.” This was a groundbreaking reinterpretation of the genre of landscape painting giving it a new level of potential significance. It reflected Friedrich’s belief that the divinity of God could be best found in nature.
Robert Macfarlane discusses the painting in terms of its significant influence on how mountain climbing has been viewed in the Western world since the Romantic era, calling it the “archetypical image of the mountain-climbing visionary”, and describing its power in representing the concept that standing on mountain tops is something to be admired, an idea which barely existed in earlier centuries.
In the foreground, a young man stands upon a rocky precipice with his back to the viewer. He is wrapped in a dark green overcoat, and grips a walking stick in his right hand. His hair caught in a wind, the wanderer gazes out on a landscape covered in a thick sea of fog. In the middle ground, several other ridges, perhaps not unlike the ones the wanderer himself stands upon, jut out from the mass. Through the wreaths of fog, forests of trees can be perceived atop these escarpments. In the far distance, faded mountains rise in the left, gently leveling off into lowland plains in the east. Beyond here, the pervading fog stretches out indefinitely, eventually commingling with the horizon and becoming indistinguishable from the cloud-filled sky.
For this composition Friedrich uses a slightly brighter palette than usual. He mixes blues and pinks across the sky with the mountain and rock in the distance echoing these colors. He paints the figure in a dark green coat – typical German attire.
Friedrich chose to paint this landscape vertically instead of the much seen horizontal orientation. The upright position of the canvas models the uprightness of the figure in the painting.