SUNDA STRAIT, Indonesia (Reuters) - Indonesia's Anak Krakatau volcano lets out a massive roar as it blasts a gigantic cloud of smoke and flaming red rocks hundreds of metres into the night sky.
A few hours later, a river of lava and stones glowing like embers glide down the slopes of Mount Anak Krakatau as the muted light of the rising sun tries to break through thick clouds settled above the mountain.
The volcano, whose name means "Child of Krakatau", formed in the Sunda Strait close to Java island after Mount Krakatau's legendary eruption in 1883. It rumbled to life about two weeks ago and since then has been dazzling scientists and visitors with its amazing pyrotechnics.
Scientists monitoring the volcano say Anak Krakatau is not especially dangerous and will continue to rumble for some time, but warn people to stay out of a 3 km zone around the mountain.
"We are a little worried sometimes when we heard the big boom and we see rocks that fall from, I don't know, half kilometre from the hole," Chad Bouchard, one of a group of eight tourists who spent the night in a boat in the ocean to watch the volcano.
"Sometimes we see the splash inside the ocean. That's a little scary but no, I think it might be stupid but I feel safe."
Anak Krakatau, which lies 42 km from the nearest observation post in Serang on the westernmost edge of Java, gradually formed after the volcanic island of Krakatau blew up in a massive eruption in 1883, triggering tsunamis and killing more than 36,000 people.
Ashes from that eruption, one of the most devastating natural disasters in recorded history, were carried by upper level winds as far away as New York City.
Krakatau, one of dozens of volcanoes in the sprawling Indonesian archipelago, last erupted in 1988, but its eruptions have never approached the ferocity of its parent.
Child of Krakatau is one of the most dangerous volcanoes in the Pacific "Ring of Fire", but authorities have not yet raised the alert level to the highest which would require the evacuation of people around the volcano.
A vulcanologist monitoring Anak Krakatau said the volcano was likely to rumble and roar for some time.
"It is still at the third level of alert. It is safe and there aren't any problems. There were approximately one hundred explosions yesterday," Saut Simatupang, head of volcano observation in Bandung, told Reuters.
"If the energy is the same as this, it is more likely it will stay at this level for quite some time as the tremors are frequent. Today only, there have been one hundred."
Visitors who had their morning coffee in a boat in the shadow of the volcano in the Sunda Strait's choppy waters about a one-and-a-half-hour ride from the mainland said they felt safe.
"It's spectacular, it's just amazing to be here," said Patricia Anderton, a tourist from New Haven in the United States.
"I feel incredibly lucky to be able to see it."