在 02-08-2026，科学家报告确认在新英格兰海岸外的海床下方存在一处大型离岸「freshened」地下水储库，显示源自陆地降雨的水可以被埋藏在海床沉积物中，并在海平面上升越过昔日海岸线之后仍可保存 1000s of years。这项发现聚焦于大陆棚下方厚实的沉积层，它们能容纳大量地下水，并引发关于如此广泛的系统如何形成、以及为何能在长时间尺度上保持被困的疑问。

利用 Expedition 501 期间自海床深处取得的岩心，Brandon Dugan 教授及其同事直接记录了横跨地下 100s of feet 沉积物的 freshened 地下水；证据显示它跨越多个沉积层，而非薄而孤立的水囊。砂质层提供了可渗透的储存与侧向扩散通道（含水层行为），而富黏土层则作为低渗透屏障（隔水层），将水挤压固定并减缓混合，帮助系统得以持续。由于离岸淡水常会部分盐化，团队追踪盐度随深度的变化，并评估盐分在岩心中移动的速度，以区分古老被困的水与沿小型通道入侵的现代海水。

一项主要的形成假说将该储库与较低海平面时期连结：当时地下水与冰期融水可补注如今已被淹没的砂层；之后海平面上升推动海水向内，而黏土限制混合；然而研究者指出，相同的模式也可能由来自陆地的缓慢现代渗漏造成，因此仍需要直接的年代测定。岩心包含出乎意料的柔软、未固结沉积物，而非完全胶结的层，意味著压实作用与连通孔隙空间可能影响跨层流动并使来源历史更复杂；同时混合带可输送氧、营养盐、氮物种与污染物，塑造海床微生物群落，并会限制任何抽水情境。在 United States，地下水供应近 1/2 人口的饮用水，且海平面上升会提高海水入侵风险，但团队并未将此发现呈现为新的水源，原因在于生态与法律上的不确定性；在探险队 1-year 等待期之后，岩心将更广泛可用，测量资料也将发布至 PANGAEA，使其能与先前的离岸测绘工作对照测试（包括一篇 2013 论文主张此类系统在全球普遍存在，以及在未钻探情况下沿 Atlantic margin 追踪远海含水层的地球物理研究）。

On 02-08-2026, scientists reported confirming a large offshore store of “freshened” groundwater beneath the ocean floor off the New England coast, showing that rain-derived water from land can be buried in seafloor sediments and preserved for 1000s of years after sea level rises over the former coastline. The discovery centers on thick sediment layers beneath the continental shelf that can hold substantial underground water, raising questions about how such a broad system formed and why it remained trapped over long time spans.

Using cores pulled from deep below the seabed during Expedition 501, Professor Brandon Dugan and colleagues directly documented freshened groundwater across 100s of feet of subsurface sediment, with evidence indicating it spans multiple sediment layers rather than a thin, isolated pocket. Sandy layers provided permeable pathways for storage and lateral spreading (aquifer behavior), while clay-rich layers acted as low-permeability barriers (aquitards) that squeezed water into place and slowed mixing, helping the system persist. Because offshore freshwater often becomes partly saline, the team tracked salt variations with depth and assessed how quickly salts moved through cores to distinguish ancient trapped water from modern seawater intrusion along small pathways.

A leading formation hypothesis ties the reservoir to lower sea levels when groundwater and ice-age meltwater could recharge now-submerged sands, followed by rising seas that pushed seawater inward while clays limited mixing; however, researchers noted the same patterns might also arise via slow modern leakage from land, so direct age dating is still needed. The cores included unexpectedly soft, unconsolidated sediments rather than fully cemented layers, implying compaction and connected pore spaces may influence cross-layer flow and complicate source histories, while mixing zones can transport oxygen, nutrients, nitrogen species, and contaminants that shape seafloor microbial communities and would constrain any pumping scenario. In the United States, groundwater supplies nearly 1/2 of the population’s drinking water and saltwater intrusion risks increase with sea-level rise, but the team did not present the find as a new water supply given ecological and legal uncertainties; after a 1-year waiting period for the expedition team, cores become broadly available and measurements will be posted to PANGAEA, enabling tests against earlier offshore mapping work (including a 2013 paper arguing such systems occur worldwide and geophysical studies tracing aquifers far offshore along the Atlantic margin without drilling).