<underground_description>Rather than adopting the usual approach of describing every side passage in the main description, which makes the 'normal' descent route hard to follow, this description describes each main route down the cave first, mentioning side passages only where necessary to make the correct main route clear. Various side passages and connecting routes are described subsequently, area by area. The directions left and right are always relative to travel in the direction of the description, compass directions are given where there is any ambiguity. Most passages are described going 'into the cave', on the assumption that this is how they will be first met. Some passages are described in both directions, either because it is difficult to follow them without getting into side leads, or because they form important links between different parts of the system, and may be traversed either way on various round trips.</p><p>The <b>clickable index</b> has developed into a <ahref="names.htm">glossary</a>, which it is hoped will make it easier to find bits of the cave by name - <b>be warned</b>, this became so big that it was decided to split it up and it is now a <b>framed</b> page.</p><p>There are also <ahref="pix.htm">virtual tours</a>, containing thumbnails of all the pictures of the caves. Although these pages are kept small, all the photos mean that they can require a <b>lot</b> of memory to load. The original comprehensive tour has been split into two, for the <ahref="pixrh.htm">Right Hand Route</a>, and for passages most conveniently reached from the <ahref="pixsf.htm">Scarface entrance</a>. Two new tours have been created for the <ahref="pixlw.htm">Lost World</a> and Wheelchair Access, and for the new way into the Forbidden Land via <ahref="pixss.htm"><spanlang="de">Steinschlagschacht</span></a>. Each thumbnail on these tours links to a full-size version of the picture, and each full-size picture has links into the appropriate bit of the description.</p><h4>Exploration</h4><p>Throughout the guide, the date of exploration is noted for each area. There is a <ahref="histry.htm">history</a> page which can be used as a clickable index into the logbook write ups of all the 161 trips, so it should be easy to follow the exploration of any part of the cave. <b>Warning</b>, this was also getting too big and is now framed.</p><h4>Overview</h4><p>The upper part of the system can be best thought of as a number of separate areas, each with its own vertical development. The more recently found extensive horizontal development, being easier to traverse, is generally better connected. Although there are various links between the vertical routes, a given destination will tend to have one 'obvious' approach. These areas are <ahref="france.htm">France</a>, the <ahref="lhr.htm">Left Hand Routes</a>, the <ahref="rhr.htm">Right Hand Routes</a>, the southernmost part of the system reached via <ahref="136.htm"><spanlang="de">Steinschlagschacht</span></a>, routes from <ahref="sftotp.htm">Scarface</a> entrance. So rapidly has exploration proceeded from Triassic Park that now more than half the total length is most conveniently reached via 161d.</p><p>The key to all the deepest and most remote parts of the system is the huge collapse chamber of Knossos. This was reached from the 161a entrance via the Right Hand Route, and now via the 161d <ahref="sftotp.htm#id161d">"Scarface"</a> entrance through <ahref="triasp.htm#triasp">Triassic Park</a>. This provides a much easier route in, making trips to the further reaches less strenuous. From Knossos, horizontal trunk passage leads north, giving access first to a series of <ahref="deepwy.htm">deep vertical systems</a>, and further on to complex areas of rifts and old passages. A significant horizontal route leading northwest, <ahref="sibria.htm#siberia">Siberia</a>, has only been pushed as a result of the new entrance, but has yielded a new deep point to the cave. There appear to be deep vertical leads in the far north, too, though they have mostly been avoided by a series of
