JSLL #15 - Urashima Tarou - Fourteenth sentence

This is sentence fourteen: short sentence, with many new kanji and words.

 青い海中をしばらく潜っていくと、急にまわりが明るくなりました。

あおいかいちゅうをしばらくくぐっていくと、きゅうにまわりがあかるくなりました。

Aoi kaichuu wo shibaraku kugutteiku to, kyuu ni mawari ga akaruku narimashita.

This is a relative clause with the particle と ("when," "whenever"), followed by a main clause.

The verb 潜っていく combines the te-form of 潜る (くぐる, kuguru), which means, "to go under," "to pass under" or "to dive (into or under the water)," with いく (the non-kanji version of 行く, "to go"). 

The 潜 kanji is an N1 kanji that occurs in 7 common words, referring to underwater stuff.

As we've seen before, the ～ていく ending indicates movement away. In this specific combination, "dove down" is probably OK, since "down" already implies "away." 

しばらくmeans "for a moment," "for a while." 

The verb also has an object (marked by を): 青い海中. (This is odd, because 潜る is an intransitive verb.) The object starts with an i-adjective, 青い (あおい, aoi). This means "blue" (although it can also mean "green" in certain contexts). The kanji is N4 and occurs in 22 common words. They're about blue or youth.

The noun that follows is 海中. Both kanji were already discussed earlier, but together they mean "in the sea," an odd translation for something that's grammatically a noun. 

The first half of the sentence, if somewhat confusing grammatically, looks like it means, "when they dove down into the blue sea for a while, ..."

The second half of the sentence starts with 急に (which means "quickly," "immediately", "suddenly"). 急 is an N4 kanji occurring in 41 common words.

Next is the subject of the main clause, まわり (marked with the subject particle が). Typically written with a kanji, 周り, this means "circumference" but also "surroundings" (the more logical reading here). 

What follows is an i-adjective (明るい, "bright") with the final -i replaced with -ku. After that is the polite past form of the verb なる, "to become," which is always written with only kana. なる always takes an i-adjective in the adverb form (ending in -く). 明 is an N4 kanji occurring in 69 common words.

So the main clause is "the surroundings quickly became bright."

"When they had dived down into the blue sea for a while, the surroundings suddenly became bright."