Sonic Sea online movie review - Superficial seeworthy docu. that establishes reality
In short: If you have not heard, viewed or otherwise gotten to know about this problem this is a good introductory documentary.
In long: This docu. does not show much new, it touches on what can partially be news to the viewer.
It's cinematographically similar to the "new" types of documentaries where the production company doesn't want to shell out on scientific experts crossed with the normal discovery docu. It does however visualise how sonar and other sound is used underwater well which is a big plus.
When it comes to the message it tries to reach out to you on a rational human level (which there is nothing wrong with) somewhat missing introducing some alternative techniques and possibly also visualising how you can do your part by whom to contact etc... Simply making sure you know that your voice is what these people are partially counting on to make change happen. It basically directs you that way with the docu. but never mentions that continuation.
Pro's ? Introductory for those unfamiliar with the subject ? Easy to grasp ? Simplyfies the subject for both good and bad.
Con's ? Does not explore a possible drop in the fishing industry as a result of sonar usage - a BIG ball to passively let drop (not following up on) after mentioning it. ? Lacks specifics (two examples - 1: about which specific technologies that could alternatively be used to what cost. 2: Specific about what studies has been made and which needs to be made on hearing-ability in fish and whales, if sonar and oil & gas ventures have a huge impact on the fishing market and it can basically eliminate it with shared ocean maps, new technology etc that needs to be clear and given time, once you can connect that dot things would change rapidly).
It touches on some solutions casually as using more Katamarans, that there are systems that negate almost all harm the oil & gas industry does with better results (new or unused technology). They also put forth that 90% of the sound from the larger shipping vessels could be removed. The solution to the latter partially being go slightly slower (with a reference to the average waiting time in dock to unload for these kinds container-ships being 3 days - which would allow the slight speed decrease).
The largest contaminating sources is the military (which is changing), the oil industry (which uses sonic bombs to map the ocean floor and its composition) and the cargo industry.