Three disc region-free Blu-ray and Region 2+4 DVD box sets were released on 8 December 2011, and include the complete series as broadcast in the UK.   In North America, the Blu-ray and Region 1 DVD box sets were released on 17 April 2012, and unlike the Discovery broadcast version, retained David Attenborough's original narration. They also include extra features not present on the UK discs: Frozen Planet: The Epic Journey , an hour-long edited highlights, and Production Video Diaries , a series of 47 video shorts made by the crew as they filmed the series. 
Well guys, regardless of how you intercept the report details given by this man and his accounts of measuring distance, I believe him. Men that do this type of work, are very accurate in recording their surroundings especially when it comes to the working for Oil Industry. I think what he meant was that knowing the waters and location of some of the nearby rigs, he knew that one was a 1 mile or so behind him and he used that territory knowledge to measure the distance between his vessel and the craft.
Another note...this cannot be related to the Oil Disaster that TX and LA suffered a few years ago. One reason is simply because the eco has been tested already after the 1st year that followed, I'm a native TX and I live on the coast. They started in the same Gulf territory after the clean up was complete and chemical engineering along with petroleum etc finished testing and deemed it safe and clear of hazard.
Secondly, come on guys...we simply aren't advanced enough to craft a flying submarine!