Exploring a cave in the woods with 探検

Kanji Explanation: Searching and probing with 探

During a camping trip, Conan and his friends are out collecting firewood when they happen upon a cave. Seeing the entrance roped off, and an obsure message carved into a rock, Ayumi, Mitsuhiko, and Genta set their gathered sticks on the ground and they head inside.

コナン:: 「おいおい　お前(まえ)ら…」; “Hey, you guys...”
歩美(あゆみ):: 「いーじゃない　ちょっと探検(たんけん)するだけだから…」; “It's okay. We're just going to explore a little.”; Literal: “Isn't it fine? Because we're only going to explore a little...”

Key Points

1探検(たんけん)する = “to explore”

In this line, 探検(たんけん) is being used as a verbal noun with する, so the phrase means “to go exploring” or simply “to explore”.
By itself, 探検(たんけん) is a noun meaning an expedition or exploration; adding する turns it into the action Ayumi says they are doing.

2ちょっと softens the proposal

ちょっと literally means “a little”, but here it also makes the idea sound lighter and less serious.
That helps Ayumi present going into the cave as a small, harmless thing.

3だけだから = “it’s only that / we’re only…”

だけ limits the action: they are only going to explore a little.
だから gives the reason behind いーじゃない: “Come on, it’s fine, because we’re just exploring a little.”