This is likely the predatory polyceridae nudibranch Roboastra cf. luteolineata. The blueish tinge to the body is not usual to this species which is normally black, but the striping and other color markings are fairly distinctive.
Image taken on the Monique Bommie dive site on the Great Detached Reef in far North Queensland, Australia. Detached Reef's in this remote area are named as they are near - but not part of - the Great Barrier Reef system.