Not every visitor to Saint-Pierre's harbour is a certified diver, and the shallower areas offer their own rewards. Several sections of the bay have accessible reef and lava formations in 3–8 metres of water, reachable by snorkel from the beach. The same volcanic activity that sank the ships in 1902 created the lava flows and rocky outcrops that now shelter fish and coral close to shore.
The clearest water and most interesting marine life are found away from the town's small fishing harbour, where boat traffic disturbs the sediment. Walk along the seafront to the northern end of the beach and enter the water there. Bring your own mask and snorkel — equipment hire is available through the dive centres in town, but availability can be inconsistent. The afternoon light, when it comes in at an angle, illuminates the shallow reef well.