Mount Karthala dominates Grande Comore at 2,361 meters, one of the world's largest active volcanoes with a crater three kilometers wide. The volcano has erupted more than twenty times since the nineteenth century, with major eruptions in 1977, 1991, 2005, and 2007. Hikers reach the crater rim through a six to eight hour ascent from villages on the volcano's southern flank, beginning before dawn to avoid afternoon cloud cover. The summit trail crosses black lava fields from recent flows, passes through scattered forest zones, and ends at the crater edge where a lava lake forms during active periods. Local guides from Moroni arrange climbs, and the route requires reasonable fitness but no technical climbing skills. The volcano releases sulfurous gases, and the crater floor changes configuration after each eruption.
Mohéli Marine Park, established in 2001, protects 404 square kilometers of ocean and coastline on Mohéli's southern shore. Green sea turtles nest on beaches within the park from November through March, coming ashore after dark to dig nests above the high tide line. Nioumachoua Beach, Itsamia Beach, and Miringoni Beach host the majority of nesting activity. Park rangers monitor nesting sites and enforce protection zones during nesting season. Humpback whales migrate through the Mozambique Channel from July through October, visible from shore on Mohéli's western coast. The park's waters hold coral formations at depths from five to thirty meters, accessible to snorkelers and divers from Nioumachoua village. Livingstone's fruit bats, a species endemic to Comoros with a wingspan exceeding one meter, roost in trees near Fomboni and fly over coastal areas at dusk.
Moroni's medina occupies the oldest quarter of the capital, a dense network of narrow stone passages between whitewashed houses with carved wooden doors. The Friday Mosque of Moroni, built in 1427, anchors the medina with a minaret visible from the harbor. Shirani Mosque sits on a rocky point where waves break against its seawall. The medina's houses display Swahili architectural elements—interior courtyards, thick coral stone walls, ventilation holes in geometric patterns. Women in the medina typically wear shiromani, a full-face covering with embroidered edges, though practice varies by family. The old port fish market operates each morning when boats return from night fishing. Vendors sell tuna, marlin, octopus, and lobster on concrete slabs near the water.
Mutsamudu on Anjouan spreads across hillsides above a natural harbor, its old quarter preserving multi-story stone houses from the nineteenth century. The Vendredi Mosque dates to the 1560s. The Sultan's Palace, a two-story structure with carved balconies, served Anjouan's ruling families until the mid-twentieth century but now stands partially ruined. Domoni, Anjouan's second town, maintains a quieter old quarter with houses built directly into hillside rock. Stone stairways connect Domoni's levels, and rainwater cisterns sit beneath courtyards. Anjouan's interior rises steeply from the coast—the island measures 424 square kilometers but reaches 1,595 meters at Ntingui summit. Vanilla plantations cover terraced slopes in the northeast, and clove trees grow throughout the uplands. Distilleries on Anjouan process ylang-ylang flowers into essential oil for export to France's perfume industry.
Lac Salé, a crater lake on Grande Comore's northern coast, sits below sea level in a collapsed volcanic formation. The lake's water maintains higher salinity than the ocean, fed by underground seepage through porous volcanic rock. No permanent streams enter or exit the lake. The lake floor lies approximately fifteen meters below the surface, and the crater walls rise steeply on three sides. Local residents report the lake's water level fluctuates slightly with tides, suggesting connection to the ocean through subterranean channels. The lake sits one kilometer from Mitsamiouli village and three kilometers from the coast.
The Coelacanth Marine Park off Grande Comore's southwestern coast protects waters where coelacanths live at depths between 150 and 400 meters. Scientists identified a living coelacanth population near Comoros in 1952, decades after researchers presumed the species extinct. Comorian fishermen call the fish gombessa and occasionally catch specimens in deep-set nets, though deliberately targeting coelacanths became illegal after 1995. Researchers estimate fewer than 500 coelacanths survive in Comorian waters. The fish occupy volcanic caves in the steep underwater slope where Grande Comore's lava base drops into the Mozambique Channel. Diving at coelacanth depths requires technical certification and specialized equipment beyond recreational limits.