Editor's note: This updates with additional details from parks in storm track.

Nearly 70 National Park System units along the Eastern Seaboard were either fully or partially closed due to impacts from "superstorm Sandy," and it could be days before some reopen.

The following rundown was provided Wednesday morning by the National Park Service:

* National Parks of New York Harbor – There is extensive flooding in Battery Park. Conditions at Castle Clinton are unknown as it is inaccessible. Con Edison is not sure when power will be restored. Subway and bus service is suspended. Most tunnels in/out of NYC are flooded.

* Statue of Liberty/Ellis Island – All electrical and mechanicals on Ellis Island are underwater; a fuel tank has been dislodged. Liberty Island may have lost all high voltage equipment.

* National Capital Region – All parks are closed with several reporting light damage and debris. Flooding is possible over the next week from rising water levels in rivers and streams.

* Assateague Island National Seashore along the coast of Maryland and Virginia – Most of the island is still under water and will be until out of lunar cycle. Park will be closed on Wednesday. Walk-in campsites have been damaged, parking lots are covered with sand and Virginia parking lots sustained significant damage.

* Valley Forge National Historical Park/Hopewell Furnace in Pennsylvania - Both parks are without power. Major roadways are open at VAFO. Trees are down and debris is scattered, but no significant damage yet found to historic structures.

* Morristown National Historical Park in New Jersey – Closed, with hundreds of trees down.

* Governor's Island National Monument in New York – One dock/pier is gone and buildings are filled with 2 to 3 feet of water.

* Fire Island National Seashore in New York – Roads are impassable and many dunes appear to be leveled. NPS boardwalks are washed out at several locations as is the Burma Road. Park headquarters appears to be ok and have power but is surrounded by water and areas with no power.

* Gateway National Recreation Area in metropolitan New York-New Jersey area – Damage from widespread overwashing. Sandy Hook is closed and inaccessible. There is damage to employees' homes and property damage at Breezy Point.

* New River Gorge National River in West Virginia – Significant snow accumulation (18-24") with more on the way. Widespread power outages.

"Our initial review indicates that there are significant safety concerns on Elliott Key -- especially given the severity of the damage to the dock. There are additional concerns due to the high amount of debris that washed up on the island," said Superintendent Mark Lewis. "We know people will be disappointed, but our primary concern is the safety of the visiting public and our employees. As we make a more complete assessment of the damages, we will keep the public informed of when the island is safe for public use."

Adams and Boca Chita Keys in Biscayne appear to have less damage, but additional evaluation was continuing in other areas of the park, including island trails, the Black Point Jetty, the sites of the park's Maritime Heritage Trail, and Stiltsville.

At Cape Lookout, which took more of a hit from the hurricane than did Biscayne, the Harkers Island Visitor Center was to open at 9 a.m. Wednesday for regular hours, though the Soundside Nature Trail remained closed due to erosion.

Officials said the seashore would be open for pedestrian use beginning at noon on Wednesday, and for vehicle use on Thursday. Vehicle ferry service also is scheduled to resume Thursday, at 9 a.m. Great Island and Long Point cabin use lodging will be open beginning at check-in time at 1 p.m. on Thursday.

At Cuyahoga Valley National Park in Ohio, officials closed the Ohio & Erie Canal Towpath Trail from Lock 39 Trailhead in Valley View to Botzum Trailhead in Akron to assess damage from the heavy rain and high winds.

In Virginia, Shenandoah National Park was closed indefinitely due to storm damage, as was Delaware Water Gap National Recreation Area in Pennsylvania.

Park Service officials also were discouraging travel along the Blue Ridge Parkway.

Acadia National Park reopened the Blackwoods Campground and park roads on Tuesday, though they were urging motorists to use caution. Also reopening Tuesday was Salem Maritime National Historic Site in Massachusetts.

Hikers thinking of heading out on the Appalachian National Scenic Trail this week were urged to postpone their trips. Several sections of the trail were closed due to storm damage.

"Impacts from flooding and tree damage from high winds are likely to be extensive. Small stream crossings will become extremely hazardous with rainfall exceeding 6-to-8 inches in some locations. Emergency response may be delayed or nonexistent due to heavily taxed resources and access issues," the Appalachian Trail Conservancy said on its website. "Cell and electronic communications may not be available for an extended period. In some areas of the trail, users should be prepared for the potential of snow accumulation that could hinder foot travel and hasten the threat for hypothermia or frostbite. Hikers should always remember their obligations to potential rescuers, and stay safe and out of trouble. This is your responsibility!"

At the Chesapeake and Ohio Canal National Historical Park, officials planned to have the park open on Wednesday, though they noted that "there will be facility closures, specifically the Great Falls Overlook Trail and Billy Goat A Trail, and additional facilities may be closed depending on local conditions. Storm damage assessments and recovery efforts will continue park-wide."