Paripurna Navasana, or boat pose looks like this:
I do this pose in my yoga for thyroid class and also use this position as the base for one of my ViPR for abdominal exercises.
The key here is to strengthen the back and the abdomen, balance equally on both left and right sit bones and open the chest as you roll your shoulders back.
Start with your knees bent, and as you progress through the years you will be able to achieve what the picture is showing, legs straight and out, body in a 45 degree angle.
There are many benefits to this pose:
Do you practice yoga? Have you done this pose?