HILO, Hawai'i — State and county officials plan to open a pedestrian trail today to a viewing area slightly more than a quarter-mile from where lava is flowing into the sea.

That spot will provide the first legal way to view lava from the ground or watch lava enter the sea since last June. For most of the past year the flows from Kilauea volcano have been concentrated at higher elevations in areas closed to the public and were visible only by air.

Dixie Kaetsu, county managing director, said county officials don't know how many people will show up after the blessing and opening today at 2 p.m., but they were bracing for sizable crowds.

"There's a lot of demand, and it's quite a spectacular thing to see right now, so a lot of people are interested in seeing it," Kaetsu said.

The county is expecting a surge of visitors in the first two days, "and if people who visit have a wonderful time and are very impressed, the word will spread and it will probably keep up," she said.

The county built an access road for lava viewing in 2001, but fingers of pahoehoe lava cut that road in two places this week, blocking access to a turnaround that cruise ship passengers and other visitors used in recent years to inspect old flows.

This week state and county crews have been improving the access road east of the portion that was just severed by lava and built a new turnaround site. Workers also marked a half-mile footpath from the turnaround to the lava viewing site.

That work was to be finished today. County officials are planning an alternate trail east of the first trail to be used if lava threatens the primary route.

State, county and federal officials will meet each morning to discuss the changing path of the lava and to decide whether the flows threaten visitors. If there is a threat, the lava viewing area will remain closed that day.

Potential hazards include brush fires and methane explosions if the lava enters forests near the turnaround, and lava could sever the pedestrian trail at a low spot near the ocean.

Wind also will be a consideration because breeze from the ocean could envelop spectators in dangerous fumes of hydrochloric acid and glass particles created by the lava when it touches the sea.

If those potential hazards aren't enough, there is a potential danger from a bench created by lava flowing into the ocean. Jim Kauahikaua, scientist-in-charge of the Hawaiian Volcanoes Observatory, said that the outcrop is about 300 yards wide and juts about 50 yards into the sea, and the bench can collapse without warning. Anyone illegally on or near the bench when it collapses could be killed.

Authorities are worried that some people may ignore the warning signs and venture too close to the flow.

The area is still closed, but county officials working in the area report they may encounter a dozen or more people at any given time who use various routes to see the lava.

County officials warn visitors there is no cell phone coverage in the area and almost no amenities, although the county has put portable toilets in two places on the access road.

County officials plan to have extra staff on hand for the first weekend and will have a mobile command post set up near the viewing area.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.