Jack Dykinga / Cenote Noh-Moson, is ringed with ficus trees with ten meter long roots reaching toward the blue water below, state of Yucatan, Mexico

Philippe Clement / European common house spider (Tegenaria atrica) in washbasin / sink next to plug-hole, Belgium

Jack Dykinga / Roots of Fig trees (Ficus sp) growing in the collapsed Cenote Oxpeejool (sink hole), near Tekax, Yucatan, Mexico. Afternoon light illuminates the elongated cavern on the right. October 2009

Jack Dykinga / Stalagmites and stalactites in underground cavern with tourquise waters of Cenote Papakal (sink hole), near Merida, Yucatan, Mexico October 2009

Jack Dykinga / Cenote Samula (sink hole) with elongated roots of a Fig tree (Ficus sp) from ground level descending to the subterranian tourquoise coloured water below. Rays of sulight pass through the hole to illum...

Michael Pitts / Barebacked fruit bats {Dobsonia sp} flying from Ormoru sink hole, Papua New Guinea

Kevin Schafer / Sandstone sinkhole and rainforest, Buraco das Araras, Mato Grosso do Sul, Pantanal, Brazil

Jack Dykinga / Stalagmites and stalactites with turquoise waters of Cenote Papakal, near Merida, Yucatan, Mexico

Jack Dykinga / Stalactites and deeply fluted formations with turquoise waters of an unnamed Cenote near Merida, Yucatan, Mexico

Jack Dykinga / Cenote Noh-Moson, is ringed with ficus trees with ten meter long roots reaching toward the blue water below, state of Yucatan, Mexico

Jack Dykinga / Calcehtok cavern, with its huge circular entrance with ficus garden and tropical vegetation descending into cave, Yucatan, Mexico

Jack Dykinga / Cenote Noh-Moson is ringed with ficus trees with ten meter long roots reaching toward the blue water below, state of Yucatan, Mexico

Alex Hyde / Male house spider (Tegenaria sp) male next to plug hole, Derbyshire, UK, September.

Philippe Clement / European common house spider (Tegenaria atrica) in washbasin / sink next to plug-hole, Belgium

Philippe Clement / European common house spider (Tegenaria atrica) in kitchen sink next to plug-hole, Belgium

Jack Dykinga / Panoramic view of Cenote Oxpeejool (sink hole) with its extensive underground chambers created by groundwater, near Tekax, Yucatan, Mexico October 2009

Jack Dykinga / Stalagmites and stalactites in underground cavern with azure waters of Cenote Papakal (sink hole), near Merida, Yucatan, Mexico October 2009

Jack Dykinga / Cenote Dzul-Ha, sink hole, light passing through hole drilled by Hacienda workers to access water below, Yucatan, Mexico. October 2009

Thomas Marent / Giant sink hole during the dry season, Ankarana Special Reserve, northern Madagascar

Tim Laman / Forest and sink hole with (Scalesia pedunculata)trees. Santa Cruz Island, Galapagos Islands, June 1993.

Tim Laman / Forest and sink hole with (Scalesia pedunculata)trees. Santa Cruz Island, Galapagos Islands, June 1993.

Pete Oxford / Sink hole now used by Macaws for nesting, Serra da Bodoquena. Limestone elevated area which divides the Pantanal and the Cerrado. Mato Grosso do Sur Province, Brazil

Pete Oxford / Sink hole now used by Macaws for nesting, Serra da Bodoquena. Limestone elevated area which divides the Pantanal and the Cerrado. Mato Grosso do Sur Province, Brazil

Patricio Robles Gil / Aerial view of sink hole, El Cielo biosphere reserve, Tamaulipas, Mexico

Patricio Robles Gil / Aerial view of Aldama sink hole, Tamaulipas, Mexico

Patricio Robles Gil / El Zacaton sinkhole or cenote with floating vegetation, near Aldama, Tamaulipas, Mexico

Patricio Robles Gil / Aerial view of Aldama sinkholes or cenotes, vertical caves filled with mineralized fresh water, Tamaulipas, Mexico

Patricio Robles Gil / Aerial view of Aldama sinkholes or cenotes, vertical caves filled with mineralized fresh water, Tamaulipas, Mexico

Pete Oxford / Daisy trees {Scalesia pedunculata} 'Gemelos' sink hole Santa Cruz Island, Galapagos Ecuador

Michael Pitts / Bare backed fruit bats {Dobsonia sp.} leaving Ormorii sink hole Papua New Guinea