After many hours, they still didn't find anything. This made Sakura a little nervous: "I can't find it."
"Why not? It should be here." Satoru questioned.
"Well, our echoscope's not picking up anything." Sakura answered.
"What about heatseekers?" Verne asked.
"I'll try that." Sakura responded.
She switched to seeking heat. And as suspected, energy was detected underneath the ocean floor.
"There it is!" she exclaimed.
"Of course." Satoru wasn't surprised, "If there was something catching the signal, it would give away some kind of heat."
"I still wonder, though, why didn't you detect anything earlier?" Verne asked.
"This system doesn't distinguish natural underground tunnels from constructed hallways." Sakura explained.
"Whatever the case, we found it." Satoru said.
"All we need to do now is find a way in." Verne stated.
"Hang on one moment." Sakura said.
She pressed a few buttons, and after a few seconds, she found a way in: "There's a tunnel underground. We can find a way in from there."
"Do it." Satoru told her.
They sank deeper, went inside the aforementioned tunnel, all up until they were directly underneath the ruins. With whatever means were at the Marine's disposal, they made a hole, large enough for it to go through. When it did, it appeared to resurface above water.
"What just happened?" Verne wondered.
"It looks like there's air in here." Satoru said.
"This should make things easier." Sakura decided.
"I'm not so sure." Verne remarked, "If there's air here, it's limited."
"Yeah, you're right about that." Satoru agreed, "We'd better henshin into our suits, that help spare us more air."
Once they had changed into their suits, they left the marine. With their helmets they could shed some light on the area. While they were at it, Boukenpink used her Accelular to scan every piece of technology they could find.
"Hazard level, zero." Boukenpink said, "Doesn't look like this will do anyone any good."
"I only hope that any precious we find here will be useful against the Atlanteans." Boukenred stated.
"Not that we'd be allowed to use it if there is." Boukemerald reminded him.
"He's made exceptions before." Boukenred told him.
"Rarely." Boukenpink remarked.
Just as she said that, something echoed through the hallways.
"What was that?" Boukenpink wondered.
"A survivor?" Boukenred stated.
"If it's not used to strangers, how do we know if it's friendly?" Boukemerald stated.
"We don't know if it's hostile either." Boukenpink remarked.
"For now, let's just look around and do what we came here for." Boukenred told them.