This soft, flowing piece was originally written for two pianos, but I listened to a flute and piano arrangement. The title means "in boat." It's very easy to picture one or two people relaxing in a small boat on a sunny day. The repeated and echoed figures throughout the song really help in creating the image of waves on a relatively peaceful lake. The piece begins with the flute in the high register with a part consisting of very simple rhythms and long tones. The piano at this time has mostly upward-moving arpeggiations. The part moves down into a lower register briefly and takes on a more playful extension of the melody. It moves back to the high register with some more long tones after a scale up in that direction. A new section begins with an increase in tempo and now the flute has a lot of dotted rhythms. This part slows down too and the piece enters a call-and-answer/echo section between the two instruments. The piano repeats a partial scale pattern that the flute played just before it while the flute plays some more long tones.
The piece as a whole consists entirely of waves of motion - there are sections full of long notes that progress into sections of quicker, more playful sections only to return to the slow, peaceful sections. It's really a great way of depicting the way small waves toss a small boat around.