var document = XDocument.Load(@"D:\test.xml");
var nodes = document.Descendants().Where(e => e.Name.LocalName.StartsWith("data"));
var values = nodes.Select(n => n.Value).ToList();
if XML is like this
<products>
<island>
<name>AAA</name>
<data>sfsgsdg</data>
</island>
<island>
<name>BBB</name>
<data>sgtyeyewy</data>
</island>
<island>
<name>CCC</name>
<data>rhjfjgfjkgfj</data>
</island>
</products>
the variable "values" contains list of values e.g {"sfsgsdg","sgtyeyewy","rhjfjgfjkgfj"}