Around 1508, Leonardo DaVinci observed a curious image of the sun
formed by a floating bubble. Now, some 500 years later, we give a full
picture of the surprisingly rich phenomenology of the light pattern
formed below surface bubbles. Under shallow illumination, and for
shallow depths of water, the caustic deviates from the symmetrical
astroid shape obtained for larger depths and/or near-vertical
illumination. Whereas the astroid caustic involves refraction through
the outer meniscus only, more complex ray paths explain the
asymmetric, multicomponent (composite) light pattern.