Ofcourse buddy, there is a lot of diving in Cornwall, Cornwall diving counts among the best in the UK. Cornwall boasts clear waters, an abundant marine life and numerous shipwrecks at depths ranging from 1-100 metres (3-328 feet).
In the months of May and June basking sharks are regularly seen as well as the orca whale and dolphins.
I can insure that it is totally worthy to dive through your trip to Cornwall, also you can check
Cornwall diving guide
Have a nice dive, looking for your feed back