Very good Ruth, You get an 'A' for knowing those dive sites are on the South tip of the Island. There is a geographic impairment in San Pedro about North and South, watch for it when your here,those afflicted with 'Southchitis' (an acute or chronic inflammation of the membrane lining of the southern lobes, caused by imbalanced Taxation infection or exposure to chambercommerce irritants).
M and M caverns are close to you and the Sandpoint dive site has turtles more often than not. Punta Azul or Basil Jones are north. I wouldn't pass up the Blue Hole trip to lighthouse reef, if you don't like the Halfmoon caye wall dive you should throw away you gear and quit.