Such connections are very difficult to make at great depths of {TAIL ~ a plurality} of hundreds of meters, with the difficulty increasing at {HEAD ~ increasing depths} 
Such connections are very difficult to make at great depths of { TAIL ~ a plurality } of hundreds of meters , with the difficulty increasing at { HEAD ~ increasing depths }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD