Many thanks to la Chcca, Seri, Leo and napalm boy for their suggestions on how to get to the center of the lake. At the end we decided to adopt the local caretòn technology and it worked!!!...well...we had to transport by hand all the rest of the equipments for the last 250 meters, after opening a path into the floating vegetation -yomomo-
Fritzcarrald would be proud of us (have you seen the movie?).