Why not house your Sony a6000, or really better a new a6300?
There's lots of housing options for both. The a6300 is a big improvement in AF and sensor and does 4K nicely.
The lenses work inside a dome port with a gear on them that is controlled by a knob on the outside of the housing.
Nauticam has a system of using a zoom lens in a flat port with it's WWL "Wet Wide Angle" lens on the outside. Or you can house the 10-18mm which is very popular underwater.
Another option is a dedicated video housing for the Sony AX100. Gates makes incredibly good housings and these are specifically designed for video and are neutrally buoyant.
You might want to read our Handbook on Buying an Underwater Camera and Housing, it will explain all the parts and pieces.
There's lots of housing options for both. The a6300 is a big improvement in AF and sensor and does 4K nicely.
The lenses work inside a dome port with a gear on them that is controlled by a knob on the outside of the housing.
Nauticam has a system of using a zoom lens in a flat port with it's WWL "Wet Wide Angle" lens on the outside. Or you can house the 10-18mm which is very popular underwater.

Another option is a dedicated video housing for the Sony AX100. Gates makes incredibly good housings and these are specifically designed for video and are neutrally buoyant.

You might want to read our Handbook on Buying an Underwater Camera and Housing, it will explain all the parts and pieces.