In Java I would like to stroke the bathymetry depth lines instead of filling the area. I'm starting with the Natural Earth Bathymetric Data: http://www.naturalearthdata.com/downloads/10m-physical-vectors/. When I apply a stroke with these files I get extra lines where the data is split into features.
Working in QGIS with the ne_10m_bathymetry_K_200 file I've tried dissolve, Polygons to lines, and in Grass tried to follow the steps outlined in this post: Dissolve polygons in QGIS (GEOS) with tolerance
No matter what I do I'm left with a stubborn line just North of Australia and a line at the right edge of the screen. If I zoom in on the line North of Australia it does look like there is a gap between these polygons.
How can I remove those last two lines?