Probably the first thing you need to know is that as they are far enough from the coast, uninhabited, and surrounded by different currents, they are an excellent location to spot a significant variety of marine life, including massive schools of giant manta rays.
You may see eels, several types of sharks, giant sea turtles, jacks, grunts, barracuda, snapper, angelfish and big schools of fish.
Some technical details for your tour:
Catalina Islands visibility conditions continuously vary without any warning. It can go from 6 to 35 meters (20 – 115 feet), meaning 15 meters (50 feet) on average. Change is due to varying levels of plankton in the area.
From mid-May to mid-December, water temperatures are generally in the span of 24-26°C (75-79°F). From December to April they may fall to 21°C (70°F) as you go deeper.
Wearing a 3mm full wetsuit could be a good idea from December to April, and a 3mm shortie is adequate for the remainder of the year.
The tour:
You will come out from the area of Flamingo, Ocotal or Coco’s beach, with experienced local dive masters that know these waters better than anyone. Therefore, they will choose the best spots for you according to the day.
If you are a true nature lover, you will love the surroundings of the Catalina Islands, with an incredible variety of fish and different sizes, shapes, and colors. Numerous species of rays are quite abundant in the isle’s waters, also including manta rays, stingrays, spotted rays, bat rays, bullseye rays, and mobula rays.
In some months it is quite common to see schools of these fantastic creatures easily swimming over you as if flying near the surface while you are deeper. With wingspans that can go from 4 to 6 meters (14-20 feet), the sight is unforgettable.
As the islands are not too far off the renowned Playa Grande, so it is not unusual to see various species of turtles swimming around.