If you're looking for manga similar to Amanchu! Advance, you might like these titles.
In a faraway archipelago to the south, there is a beautiful, sun-drenched island with pristine beaches, gentle waves, and a laid-back atmosphere. Umi Kohama was raised on the island and works as a diver. Along with her coworkers and other residents, Umi enjoys her idyllic life.
Ji-Eun, a children's storybook author goes to Guam for her friend's wedding. There, she develops a strong fascination with the ocean and decides to become a diver. As a scuba diver and free-diver, she experiences the universe beneath the earth, a new life, and people who love the sea, and explores lost dreams, love, and the meaning of life.
Salvors are men responsible for towing wrecked ships and handling the cargo. They are different from rescue teams as they usually ask for money before offering help. Nanba Rintarou's father was the owner of such a company, but Rintarou really hated the way they operated and decided to join the Coast Guard. However, Rintarou's father died right after Rintarou completed his training. In his will he asked Rintarou to take over his company. What's worse is he left his son a debt of 1.5 billion yen...
Due to family reasons, Ako moved to the countryside. Far from her friends, Ako was feeling lonely when a cute cat came to her. The heart-warming life between a junior-high schoolgirl and a special kitty.
One hundred and fifty years after its terraforming, the surface of the planet Aqua - formerly known as Mars - is almost completely submerged by water. The town of Neo Venezia, a replica of the old Earth city of Venice, is a city that lives in harmony with the water, and is a popular destination for tourists. Akari Mizunashi is a young girl who dreams of becoming a fully fledged Undine - a gondolier who ferries tourists around the beautiful city. With help from her friends she progresses with her training, discovering more of the many wonders of Aqua and Neo Venezia along the way.