. ▁Today , ▁this ▁route ▁to ▁Pool ▁Chamber ▁forms ▁part ▁of ▁the ▁walking ▁section ▁of ▁the ▁show ▁cave . ▁▁ ▁Mart el ▁and ▁James on ▁also ▁investig ated ▁C rad le ▁H ole , ▁a ▁very ▁large ▁surface ▁sh ake hole ▁ ▁south - s outh - west ▁of ▁Mar ble ▁Arch . ▁A ▁cave ▁entrance ▁in ▁the ▁north - e astern ▁corner — Lower ▁C rad le — was ▁expl ored , ▁reaching ▁an ▁under ground ▁river ▁and ▁pass ages ▁with ▁the ▁same ▁proport ions ▁as ▁those ▁in ▁the ▁Mar ble ▁Arch ▁C ave . ▁▁ 1 9 0 7 – 1 9 0 8 : ▁Great ▁B ould er ▁Chamber ▁and ▁d ye ▁trac ing ▁ ▁In ▁ 1 9 0 7 , ▁English ▁ca vers ▁from ▁the ▁York shire ▁R amb lers ' ▁Club ▁began ▁expl oration ▁in ▁the ▁area , ▁and ▁without ▁access ▁to ▁a ▁boat ▁they ▁decided ▁to ▁w ade ▁the ▁section ▁of ▁under ground ▁river ▁as ▁far ▁as ▁The ▁J unction , ▁subsequently ▁reaching ▁the ▁extent ▁of ▁Mart el ▁and ▁James on ' s ▁expl or ations . ▁Bol ster ed ▁by ▁the ▁experience , ▁and ▁the ▁good ▁possibility ▁of ▁further ▁discover ies , ▁the ▁York shire ▁R amb lers ▁returned ▁in ▁E aster ▁ 1 9 0 8 . ▁A ▁group ▁of ▁ca vers ▁desc ended ▁a ▁p oth ole ▁located ▁close ▁to ▁the ▁large ▁dol ines ▁on ▁the ▁plate au ▁and ▁discovered ▁the ▁Great ▁B ould er ▁Chamber . ▁After ▁a ▁few ▁hours ▁of ▁expl