^^ Mostly parking. Underground parking is expensive in Dubai because of problems with water, that's the reason why the towers at SZR have seperate carparks at the back. Some towers still have underground parking though, especially the massive ones with lots of units like princess tower.
All those podiums will be attatched to each other and eventually a mall will be built in between the row where marina 101 is and the one behind it where the pentominium is.
I don't think it's mandatory that all towers have shops at the base though, some definitely will have them but not all, most of the public facilities will be at the water's edge anyway.
Updates of the torch:
Major sections of shear walls are visible within the slip form.
The bottom right of the photo shows the rebar ready for the casting of the top the water tank. Since this photo was taken 2 days ago this has now been complete. Some of the major columns and Shear walls are visible here already cast for the support of the first car parking level.
Rebar continue to flow onto the construction site to keep up with the accelerated work of the columns and core of the building.
First level of the car park cast visible cover about a third of the total basement area. The red steel frame work is the sliding form work, which give s a template for the main core structure of the building and will follow all the way to the top of the building as each floor is cast.
Major reinforcement being worked on for above the first level of the car parking floors.
Sections of spare crane on site for when the cranes need elevating further.
First floor of the car parking level being prepared for casting. Each of the car park floors are 345mm thick reinforced concrete. This will also provide the under cover area for the workers to take shade that becomes a necessity in the summer.
Updates of 23 marina:
Some renders of this area from street level:
