Lake Junín, located at ~4100 m asl in the inner tropics of the Southern Hemisphere, is a prime target for drilling because it contains a thick (>200 m) sediment package deposited at a high rate (0.2 to 1.0 mm yrF1). Moraine mapping coupled with cosmogenic radionuclide dating indicate that paleoglaciers reached the lake edge, but have not overridden the lake in one million years, or more. Lake Junín is thus one of the few lakes in the tropical Andes that predates the maximum extent of glaciation and is in a geomorphic position to record the waxing and waning of glaciers in nearby cordillera. The lake also contains ideal sediments for multiproxy analysis that can be reliably dated using both the radiocarbon and UFTh methods. The oxygen isotopic composition of marl and ostracod carapaces recovered in multiple preliminary cores covering the last 50 ka demonstrate that the d18O of authigenic calcite primarily records the isotopic composition of precipitation and secondarily the degree of evaporative enrichment of lake water. Lake Junín contains a continuous record of tropical hydroclimate over interglacial and interstadial intervals for much of the past several hundred thousand years that both complements and significantly extends stable isotope records from regional ice cores and speleothems.