Lake Lancaster Arriba (Spanish: Laguna Lancaster Arriba), together with Lake Lancaster Abajo are part of two lakes in the Limón province of Costa Rica, collectively referred as the Lancaster Lakes.

[1] The Lancaster lakes are located in a private property next to Reventazón River, and 7.35 kilometers SW of the Reventazón Dam.

[2] Lake Lancaster Arriba is of landslide origin and its surface is almost completely covered by aquatic vegetation including hyacinths and ferns.

[3] At the time of the construction of the Reventazón Dam, in 2016 and 2017, local preservation groups exposed that the wall between Reventazón river and Lake Lancaster Arriba was being excavated for raw materials for the dam.

After a series of investigations, no such action was confirmed.