Hi, the code below was added to SeaGenerater.java in revision 1760. Since then the some flooding happens in a few tiles. before that all sea rendering was correct. I tried also the floodblocker but then part of the sea is not blue anymore. It jsut blocks sea in some places but doesn't prevent the creation of bad polygons. I have checked all of the coastline and it is definitely correct and extends in all places beyond the bounds of the tile. If someone want's to debug I can also provide the coastline only for the area. Just too big for this list and can upload or send to a private email I am using generate-sea=multipolygon,extend-sea-sectors,close-gaps=10 area for splitter is 18900004: 1687552,-5750784 to 1761280,-5685248 # : 36.210938,-123.398438 to 37.792969,-121.992188 This is the code difference in SeaGenerator.java if (clipped.size() > 0) { // the LineClipper sometimes returns unjoined clips // need to rejoin them here log.info(clipped.size(),"clippings. Try to join them."); List<Way> clippedWays = new ArrayList<Way>(clipped.size()); for (List<Coord> clippedPoints : clipped) { clippedWays.add(new Way(FakeIdGenerator.makeFakeId(), clippedPoints)); } clippedWays = joinWays(clippedWays); if (clippedWays.size() != clipped.size()) { clipped = new ArrayList<List<Coord>>(clippedWays.size()); for (Way w : clippedWays) { clipped.add(w.getPoints()); } } log.info(clipped.size(),"joined clippings."); }