This a big challenge so allow plenty of time for this puzzle.
There are substantial areas of plain green and plain blue with no distinguishing features. The pieces are not particularly well cut making it easy to put a piece in the wrong space, and finish with a number of pieces which do not fit the remaining spaces. In addition there is a large area of blue with only a very faint printed design: the illustrations on the box cover are much smaller than the finished puzzle making it difficult to identify individual pieces.
However, the finished result is worth the effort..