Travel writing is a special type of descriptive literature that can involve a great deal of detail about specific venues, such as cities, countries, and/or regions. The best travel writing includes information not only on the best places to stay (e.g., the better and more affordable options with respect to hotels, bed-and-breakfasts, youth hostels, etc.) and the most popular and less-popular-but-still-worthwhile sites, but also provides insights into the local culture, including artistic and culinary attributes, and history. Every location has its unique characteristics, and it is the travel writer's responsibility to identify and describe those characteristics, including the negative aspects of specific locations, such as neighborhoods with high crime rates that travelers should avoid. Cultural attributes, such as festivals, concerts and other events unique to a specific location (e.g., the annual Mozart celebration in Salzburg; Octoberfest in Munich) that may aid prospective travelers in scheduling their visits.
With respect to Sri Lanka, the task of the travel writer would be to capture that island nation's natural beauty -- and Sri Lanka, which lies off the southeast coast of India, is abundant in natural beauty -- while providing the usual tips regarding optimal places to stay and visit. Sri Lanka, however, is no ordinary venue. For several decades, from the early-1970s to the 2002 ceasefire that ended armed hostilities, Sri Lanka was the sight of a brutal civil war between its majority, Buddhist Sinhalese, who make up around three-quarters of the island's population, and the minority Hindu Tamils, who waged a fierce insurgency led by the Liberation Tigers of Tamil Eelam, a particularly ruthless guerrilla army that carried out numerous acts of terrorism against its Hindu rivals. That civil war made travel to Sri Lanka for recreational purposes problematic at times, and the country continues to carry the scars of that conflict. A travel writer seeking to capture Sri Lanka's atmosphere today would need to reference those scars and the continuing animosity between ethnic groups that exists.
Travel writing is what your experience was like at a place. How you felt, what you saw, what is different from what you know. Hopefully, you are giving an honest response.
Travel writing requires a person to travel to a particular location, in your case, Sri Lanka. You would need to write about something you observed and/or experienced. If you like to try out different foods, you essay might contain information related to the cuisine you sampled. If you like to visit religious/spiritual areas you would write about what you experienced upon your arrival at that place. You would probably want to entertain your reader as well as give them information that they would not otherwise be able to learn.