2   m ) ▁deep . ▁Both ▁of ▁these ▁sh aft s ▁were ▁filled ▁with ▁water ▁when ▁an ▁alleg ed ▁flo od ▁tunnel ▁was ▁again ▁bre ached . ▁At ▁one ▁point ▁one ▁of ▁the ▁platforms ▁placed ▁in ▁the ▁original ▁sh aft ▁at ▁ 9 8 ▁feet ▁( 3 0   m ) ▁col lapsed , ▁and ▁dropped ▁to ▁a ▁lower ▁level . ▁The ▁effect ▁caused ▁the ▁next ▁two ▁platforms ▁to ▁drop ▁as ▁well ▁with ▁the ▁tre asure ▁now ▁rest ing ▁some ▁ 1 1 9 ▁feet ▁( 3 6   m ) ▁below ▁ground ▁along ▁with ▁an ▁estimated ▁ 1 0 , 0 0 0 ▁feet ▁( 3 0 4 8   m ) ▁of ▁l umber . ▁The ▁first ▁of ▁six ▁accident al ▁death s ▁during ▁exc av ations ▁occurred ▁during ▁the ▁fall ▁of ▁ 1 8 6 1 ▁when ▁a ▁p ump ▁engine ▁bo iler ▁burst . ▁The ▁explos ion ▁was ▁first ▁mentioned ▁in ▁an ▁ 1 8 6 3 ▁novel ▁titled ▁R amb les ▁Among ▁the ▁Blue - n oses , ▁while ▁mention ▁of ▁a ▁death ▁came ▁five ▁years ▁later . ▁Another ▁sh aft ▁was ▁d ug ▁in ▁the ▁spring ▁of ▁ 1 8 6 2 , ▁one ▁which ▁was ▁ 1 0 7 ▁feet ▁( 3 3   m ) ▁deep . ▁This ▁new ▁sh aft ▁was ▁parallel ▁to ▁and ▁connected ▁with ▁the ▁original ▁sh aft ▁as ▁it ▁was ▁used ▁to ▁p ump ▁water ▁out ▁of ▁the ▁original ▁sh aft ▁to ▁a ▁depth ▁of ▁ 1 0 3 ▁feet