Spatially adaptive sampling is necessary to resolve evolving gradients with sparsely distributed sensors. Assessing the reality of numerical model fields with ever increasing resolution, testing dynamical balances involving high-order derivatives, and exploring the limits of predictability require measurement of temporal and spatial gradients in the ocean far exceeding current practical capabilities. Sensors for various properties have improved steadily in recent years, capitalizing on advances in electronics, fiber optics, and materials. In contrast, platforms enabling measurement of property gradients remain primitive. With current trends, advances in a large class of ocean science problems will be increasingly platform limited.