In the travel agency the petrol is one of the biggest external factor that the reason the orice go up or down.As well the weather is really important if it's good weather where the people leave they don't travel as much or if is really bad people want to go away.The competitors are really important if they put the price down or up, you will need to do the same other wise no one is going to buy from you.Internet is really important if you have as well a web site you might sale more.The economy and the politique in the country might affect the travel industry.