Tomasee

{{Short description|Lake in Switzerland}}

{{See also|Sources of the Rhine}}

{{Infobox lake

| name = Lake Toma ({{lang|de|Tomasee}})

| other_name = Lai da Tuma

| image = Tomasee 2.JPG

| caption =

| image_bathymetry =

| caption_bathymetry =

| location = Grisons

| coords = {{coord|46|37|57|N|8|40|20|E|type:waterbody_region:CH-GR_source:dewiki|display=inline,title}}

| type =

| inflow = Rein da Tuma

| outflow = Rein da Tuma

| catchment =

| basin_countries = Switzerland

| length =

| width =

| area = {{convert|2.5|ha|abbr=on}}

| depth =

| max-depth =

| volume =

| residence_time =

| shore =

| elevation = {{convert|2345|m|abbr=on}}

| islands =

| cities =

| pushpin_map=Canton of Graubünden#Canton of Uri#Switzerland#Alps

| pushpin_label_position= bottom

| embedded = {{Infobox mapframe |wikidata=yes |zoom=16 |coord={{WikidataCoord|display=i}}}}

}}

Lake Toma ({{langx|de|Tomasee}}, {{langx|rm|Lai da Tuma}} or {{lang|rm|Lag da Toma}}) is a lake at the northern face of Piz Badus, above the village of Tschamut in the canton of Grisons ({{lang|de|Graubünden}}), Switzerland. Its surface area is {{convert|2.5|ha|abbr=on}}.

It is the source of the Anterior Rhine and is deemed to be the official source of the Rhine (the source of the Posterior Rhine is above Hinterrhein, Switzerland, at {{coord|46.499|N|9.065|E|region:CH-GR_type:river|name=Source of Hinterrhein}}).

It is possible to reach the lake on a path from Oberalp Pass, suitable for most walkers although still a mountain trail.{{in lang|en}} [https://maps.graubuenden.ch/en/tour/hiking-trail/to-the-rhine-source-oberalp-pass-lake-toma/14511607/ Hike Switzerland to the source of the Rhine in Graubünden]

File:Rhine source.JPG