Terrigal
Terrigal is where diving all started for me. I learnt to dive in Terrigal Haven with Les and Fran Graham.
Whilst Terrigal now features the ex-HMAS Adelaide (scuttled April 2011 off North Avoca beach), it has always been a fantastic jumping off point to some very good diving. The area has some brilliant shore diving, some excellent reef diving as well as some very nice deep wrecks. The coast north up to Norah Head or south to Broken Bay is quite accessible from Terrigal but you certainly don't need to travel that far to find a good dive.
Being another very popular holiday and weekend spot on the coast, there is plenty of accommodation. If you are looking for a place to pitch a tent you will need to stay a bit further north around Bateau Bay or down south in Bouddi National Park.
There is a good boat ramp at Terrigal Haven or you can use one of the 3 Commercial Operators for your boat diving. These operators seem to be quite focused on diving the ex-HMAS Adelaide but I am sure that over time, demand for reef and other wreck diving will increase as regular divers in the area again desire a little more variety in their diving.