Ask your dive operator about the following noted dive sites. Sometimes to keep diving affordable some dive sites are not often visited - be firm if you really want to visit a particular site with any dive operator on any island but please take into account the extra effort to reach the sites. They might have a different price for some sites to cover the extra diesel. Hard core divers will situate themselves in a specific dive resort for this reason. There are no specific dive resorts on Antigua, however Sandals do go diving for their guests but it isn't included in the all inclusive.
Antigua dive sites worth mentioning
Most of the best dive sites in Antigua are around cades reef. This is also one of the main spots for snorkelling. Your dive operator may do cades reef regularly.
Out in the seeming middle of nowhere you can get down to 22m here and maybe get lucky enough to see some sharks. The reef is healthy and part of the Cades Reef System. This site was found when the Antigua Boat Yacht race markers were installed.
Pillars of Hurcules
The Pillars are above the water but boulders and good coral make this dive site one of the best on the island and the south side.
For snorkeling in Antigua there is an interesting wreck at the mouth of Deep Bay the Andes wreck is nice - but is a bit of a swim out beware of jetskis.