From Miller and others (1998)
[1]: "Ukinrek Maars are a pair of phreatomagmatic explosion vents that formed on a low (less than 100 m high), 4-km-long, ridge in the Bering Sea Lowland 1.5 km south of Becharof Lake and 12 km northwest of Peulik Volcano. West Maar, elliptical in shape and up to 170 m in diameter and 35 m deep, formed on the northwest end of the ridge
[2]. East Maar lies 600 m east of West Maar at a lower elevation. It is circular, up to 300 m in diameter and 70 m deep, and has a 49-m-high central lava dome that is now partly covered by a crater lake. Location of the maars apparently coincides with, and may be controlled by, the intersection of the Bruin Bay fault and regional structures
[2] [3]"