subdomains, wordpress and html

I have an older html site, which I plan to turn into a subdomain and will be using wordpress for the core site(the Bay) and wordpress for the other subdomains (Islands).
The core site will be in WordPress and will be about a bay, and the many islands in the bay will be subdomains. The existing older site (which is about one island), which is in html, will be transferred to another subdomain.
Question: Is their a plugin to produce a sitemap for this diverse group of html and wordpress?
Also do you know of any other major issues I may encounter?