I assume you're asking about the area in the Firth of Thames between Thames and Coromandel (town). I have not dived in that area at all. Might depend on your definition of 'alright vis' as hearsay from other divers would suggest the viz in the Firth of Thames is quite poor.
p84-p85 of the Diving New Zealand Spot X Guide (1st edition) lists dives in that region. However all the dives listed look like they're on the islands, requiring a boat, except #9 at Waitete Bay (north of Coromandel) that is listed as a scallop dive.
If you don't get any good advice, perhaps you can explore and report back.