In my very first post on this blog, I wrote about Lake Jezioro on Mars. Its name means Lake Lake. Lake Lake on Mars – Language Miscellany
I recently came across an example on Earth, and in fact went for a boat trip on that lake. Lake Rotomahana in New Zealand has a name meaning ‘warm lake’ in Maori’. (roto = lake, mahana = warm). So, Lake Rotomahana is Lake Warm Lake.
Lake Rotomahana sits in a crater formed by the eruption of Mount Tarawera in 1886. That massive eruption created the only geothermal system to have come into existence since written history began. Before the eruption, a much smaller lake of the same name (Lake Rotomahana) occupied part of the area obliterated by the crater. Alongside the old Lake Rotomahana sat an even smaller lake, Lake Rotomakariri. It’s easy to see why the local inhabitants picked that name to contrast with Rotomahana: makariri means cold.
Perhaps the best-known place whose name starts with Roto is the geothermal spa resort of Rotorua (rua = 2, so Rotorua is Lake 2 or second lake.)
Altogether, 17 places names containing the first element Roto-are listed at 1000 Māori place names – Te Wiki o Te Reo Māori – Māori Language Week | NZHistory, New Zealand history online And several other names listed there have -roto as the last element.