A trekking operator with more ambition than most: besides Laguna Esmeralda it runs Laguna Turquesa, the Vinciguerra glacier, Monte Susana, and an overnight camp at the Ojo del Albino glacier. A photographer can come along on some trips.
The WhatsApp is the widget on their site. The tourism secretariat's register lists the office on Belgrano; the pin marks that street.