Lake Mainit is the fourth largest lake in the Philippines, having a surface area of 173.40 square kilometres (66.95 sq mi). The lake is also the deepest lake in the country with maximum depth reaching 223 metres (732 ft). It is located in the northeastern section of Mindanao and shared between the provinces of Surigao del Norte and Agusan del Norte.

The name of the lake is a Visayan word mainit, which means "hot".

• Fire orchid (Vanda hookeriana)
• Narra tree (Pterocarpus indicus)
• Molave tree (Vitex parviflora)
• Philippine rosewood or "toog"
• Kamagong
• Mancono
• Malabayabas (Eucalyptus spp.)
• Indian lotus (Nelumbo nucifera)

• Animals

1. Mindanao scops owl
2. Mindanao savanna nightjar
3. Mindanao Himalayan swiftlet
4. Mindanao forest kingfisher
5. White-breasted sea eagle (Haliaeetus leucogaster)
6. Monkeys
7. Wild pigs

• Fish

1. "Casili" (Anguilla spp.)
2. Mudfish, "hayuan" or "halwan" (Channa striata)
3. Gurami (Gourami belontiidae)
4. "Bolinao" (Neostethus thessa)
5. Common carp (Cyprinus carpio)
6. "Tilapia" (Oreochromis niloticus)

• Mainit, Surigao del Norte
• Alegria, Surigao del Norte
• Jabonga, Agusan del Norte
• Kitcharao, Agusan del Norte

• A Directory of Philippine Wetlands. Vol I, compiled by Davies, J. et al. (Asian Wetland Bureau Philippines Foundation, Inc, 1991)
• Webpage on Lake Minit (cited part available online)

• Geographic data related to Lake Mainit at OpenStreetMap
• Lake Mainit Updates
• Lake Mainit Development Alliance
• LMDA Updates