I am just put my 7d in an Ikelite housing and would like to know what marco lens would be recommended to use with it.

Thanks

Depends a bit. I use the Canon 60 which is a great lens, fast focus and quite nice image quality. The downside is no use of a 1.4 tele. The new Tamron 60 is not quite as nice optically (when pixel peeping) but can use a 1.4 tele. I just got one but haven't had it in the water yet. It is a bit longer than the Canon so I need a port extension to use it. At the harder to use end of the spectrum is the Canon 100 which is the sharpest lens I own but needs a lot of practice to shoot well. I would start with one of the 60s and go from there.
Bill

ANother vote for the 60mm EFS macro lens.

I concur.