A species of burrowing shrimp was able to tolerate ocean acidification conditions (pH 7.64) for 35 days. At a lower pH of 7.35, individuals experienced extracellular acidosis, suggesting they had little or no buffering capacity, although there was no evidence of negative impacts on metabolism, osmotic regulation, shell mineralogy, growth, or overall activity. At pH 6.71, all individuals died; importantly, this extreme level of acidification exceeds projections for ocean acidification for this century but could potentially occur in the vicinity of carbon sequestration facilities.