Hi The sea polygon patch uses a feature from java 1.6 (NavigableSet), whereas mkgmap is currently released for java 1.5. Perhaps there is a different way to do it that avoids the use, but it could be time to consider going to 1.6. Now I don't personally mind going to 1.6 and in fact I announced that this would 'happen soon' over a year ago. The only problem is people with Macs. As I have experienced with splitter (which always has required 1.6) there were quite a few queries to the mailing list and to my own email address from people not being able to run it. As there are many more downloads of mkgmap than splitter, I expect that there would be far more queries generated for mkgmap. Now as far as I know, it is no longer a problem getting 1.6 for all Macs, so I don't think anyone will be unable to run it, it is just a case of knowing what to download from where for which Mac 32/64 bit etc. So if we were to start requiring 1.6 I would like to prepare by adding a specific error message to mkgmap stating the version requirements, rather than just a stack trace that you would currently see, and to get a description of how to obtain 1.6 for the different Macs that can be placed on the wiki and web site etc. What do you think? ..Steve