Travel within one's own country; domestic travel for sightseeing or vacation to cities and tourist spots.
今年の夏は家族で国内旅行に行く予定だ。
This summer my family plans to go on a domestic trip.
温泉に行くなら国内旅行のほうが気軽でいい。
If you're going to a hot spring, domestic travel is easier and more convenient.
国内旅行で地方の郷土料理を楽しんだ。
I enjoyed local cuisine during my domestic trip.