Dived yesterday and today, water temp around 14 deg C. Viz around 12m. Shorediving as previously mentioned is definitely a possibility at this time of year.
Other species to look for - Haploblepharus edwardsii, Haploblepharus pictus, Poroderma pantherinum. There are sixteen species found around Southern Africa, four of which are commonly found in Cape Town waters.
A couple of friends of mine have written books on marine life specific to Cape Town, shout if you need help, someone to dive with or to point out locations for you.