I'm trying to build a sea-only map for Spain to combine it later with my routeable map. What I've done is: 1-Download natural=coastline ways for the desired bbox [1]. 2-Edit downloaded osm file in JOSM and close the land polygon in the North. I used segments of some 60 km for that. I can put resulting file on my site if anyone wants to download it. 3-Run mkgmap with the following options: java -Xmx500m -enableassertions -jar mkgmap.jar --generate-sea --latin1 --code-page=1252 --description="Costa Iberia" --family-name="Open Street Map" --family-id=20 --product-id=320 --series-name="OSM-Iberia-costa" --mapname=63240100 --tdbfile --style=sea --draw-priority=28 --transparent /home/carlos/JOSM/costa_peninsula.osm And I get the error below: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.RangeCheck(ArrayList.java:547) at java.util.ArrayList.get(ArrayList.java:322) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5XmlHandler.concatenateWays(Osm5XmlHandler.java:1332) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5XmlHandler.generateSeaPolygon(Osm5XmlHandler.java:1071) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5XmlHandler.endDocument(Osm5XmlHandler.java:557) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endDocument(AbstractSAXParser.java:737) at com.sun.org.apache.xerces.internal.xinclude.XIncludeHandler.endDocument(XIncludeHandler.java:1119) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:515) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205) at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522) at javax.xml.parsers.SAXParser.parse(SAXParser.java:395) at javax.xml.parsers.SAXParser.parse(SAXParser.java:198) at uk.me.parabola.mkgmap.reader.osm.xml.Osm5MapDataSource.load(Osm5MapDataSource.java:80) at uk.me.parabola.mkgmap.main.MapMaker.loadFromFile(MapMaker.java:148) at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:56) at uk.me.parabola.mkgmap.main.Main$1.call(Main.java:187) at uk.me.parabola.mkgmap.main.Main$1.call(Main.java:185) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) Does anyone know what is the problem? [1] wget http://osmxapi.hypercube.telascience.org/api/0.6/way%5Bnatural=coastline%5D%... -O costa_peninsula.osm