what is advanced open water SCUBA?

Answer 1

There are a few kinds of international diving certificates. One of these systems is by the Australian PADI institute.
In the PADI system, you can do a 4 day course for an Open Water certificate. With this, any diving center in the world will let you dive with them for a fun dive. It's proof that you know the basics and have done a few dives to a depth of 18 meters. The second level, after another 4 day course (book knowledge and practice dives) is Advanced Open Water. In advanced open water, you've practiced a dive to 30 meters, a night time dive, and simple under water navigation. The PADI system offers several more courses and specializations after that.