▁ ▁At ▁the ▁inv itation ▁of ▁Boston - area ▁business man ▁David ▁M ug ar , ▁a ▁two - week ▁survey ▁was ▁conducted ▁by ▁the ▁Wood s ▁H ole ▁Ocean ographic ▁Institution ▁in ▁ 1 9 9 5 ▁( the ▁only ▁known ▁scientific ▁study ▁conducted ▁on ▁the ▁site ). ▁After ▁running ▁d ye ▁tests ▁in ▁the ▁bore ▁hole , ▁the ▁institution ▁concluded ▁that ▁the ▁flo oding ▁was ▁caused ▁by ▁a ▁natural ▁interaction ▁between ▁the ▁island ' s ▁fresh water ▁l ens ▁and ▁tid al ▁press ures ▁in ▁the ▁underlying ▁ge ology ▁( ref uting ▁the ▁man - made ▁tunnel ▁theory ). ▁The ▁Wood s ▁H ole ▁scient ists ▁who ▁viewed ▁the ▁ 1 9 7 1 ▁videos ▁reported ▁that ▁nothing ▁conclus ive ▁could ▁be ▁determined ▁from ▁the ▁mur ky ▁images . ▁The ▁reported ▁five ▁finger ▁( or ▁box ) ▁dra ins ▁at ▁Smith ' s ▁C ove ▁have ▁recently ▁been ▁thought ▁to ▁be ▁the ▁remains ▁of ▁an ▁early ▁salt ▁works , ▁with ▁no ▁connection ▁between ▁the ▁dra ins ▁and ▁any ▁flo oding ▁of ▁the ▁pit . ▁ ▁Oak ▁Island ▁lies ▁on ▁a ▁gla cial ▁tum ulus ▁system ▁and ▁is ▁under lain ▁by ▁a ▁series ▁of ▁water - filled ▁an h yd rite ▁cav ities ▁which ▁may ▁be ▁responsible ▁for ▁the ▁repeated ▁flo oding ▁of ▁the ▁pit . ▁This ▁type ▁of ▁lim estone ▁easily ▁dissol ves ▁when ▁exposed ▁to ▁water , ▁forming ▁c aves ▁and ▁natural ▁void s . ▁Bed rock ▁lies ▁at ▁a ▁depth ▁of ▁ ▁in ▁the ▁pit ▁area . ▁ ▁Stone