Corrections in red.  Stylistics in blue.

SOUTH AMERICA:

is the fourth largest of the continent, with an approximate area of 18 million sq.kms/7 million sq. miles, or with reference to one-eighth of the world’s surface. [1] . . . . It is washed by the Caribbean Sea on the northwest, by the Atlantic Ocean on/in the north, east, and south, by Drake Passage on/in the south, and by the Pacific Ocean on/in the west.  It is joined to North America by the Isthmus of Panama. As this continent includes such a colossal number of countries, cultures, rise above patterns ?? [2] and landforms (tropical rainforests, majestic mountains, deep gorges and valleys, and countless lakes), it is a haven for hikers and bushwalkers. [3]

[1] tarmac is a substance used to construct roads and airport runways.  

[2]  I do not understand ""rise above patterns".  

[3]  I had never heard the word "bushwalker" before.  It appears to be a term mostly used in Australian English.