Here is a documentary about the quicksands, available in French :
https://www.youtube.com/watch?v=QXeXyRBlFbU




Horror films have offered many scenes where a person was hopelessly sucked into quicksand. Although this keeps its mystery, scientists were able to determine how these mixtures of sand and water are in motion and swallow everything that comes along. They also determined the places in the world where the shifting sands are, and explain how to extract. Survivors and relatives of victims recount their experience this terrifying force of nature. The spectacular images of the rescue of a horse by helicopter crown this immersion in a strange universe, as fascinating as dangerous.
http://forums.france5.fr/france5/La-gal ... et_4_1.htm
There are 4 stories with 4 differents locations.
I asked the youtuber to add the end.
I don't know if there are already the original version somewhere here...