California's first cult sparkling wine—and this single-vineyard Blanc de Blancs from Keefer Ranch may be its most compelling expression. Michael Cruse founded Ultramarine in 2008 after studying molecular biology at UC Berkeley, applying scientific precision to traditional-method sparkling wine from Sonoma's coolest sites. Keefer Ranch sits in the Green Valley of Russian River Valley—the foggiest sub-appellation in Sonoma—where Goldridge loam soils and an eastern-facing slope produce Chardonnay of extraordinary freshness and complexity. Hand-riddled, hand-disgorged, with just two grams per liter dosage. The 2018 vintage returned to classic timing after several warm years, with a late, cool growing season preserving acidity and building nuance. Orchard fruit, jasmine, mint, and crushed rocks with soft contours and a persistent mineral finish. Fewer than a few hundred cases produced. For those who believe California can rival Champagne.