Found four or five of these water beetles hiding mid afternoon under object (rock I think) near small puddle on bed of Rio Grande.

Both banks of the river are in New Mexico at this point, ten or so miles north of the Mexican border, so their nationality is not suspect ;-).

Air temperature was in 60s but lingering cold from the prior night probably made it 20 degrees cooler in their hiding place. They were accompanied by one water beetle of another species.

This image is a composite of five other images combined by Helicon Focus (see discussion and original images).