The last of the Icicle Cluster levels, Cerulea is also quite large. Its objectives aren't far from average, but due to the layout, it may take you a while to solve. There is also a teleporter in this level, except if you have already visited the secret level (via Pelorus) you won't be able to return.
This mine follows the usual blue - yellow - red key system, except you will need the two hostages before you can proceed. The major threat here comes from IDR and Sniper-RF combinations.