There are many ways to get data from the web and after retrieving the data using serialisation may be overkill so using XPath is a simple way of obtaining elements from XML, as this is a simple document you could simply use:
//elevation
but this can give you a list of all nodes of tag 'elevation' and there are ways to single out certain tags using criteria.
https://www.w3schools.com/xml/xpath_syntax.asphth