Long Vacation: Iruka to Watashi is a simulation game in which the player can interact as they wish with their virtual animal, a dolphin.

The player begins by giving the name of his choice to his dolphin. He also has the possibility to choose his color. Four are available in total: blue, pink, gray or white.
Then he can interact with him as he wishes. Through the touch screen and using the stylus incorporated into the Nintendo DS, he can, for example, stroke it. He can also play with him in different ways, such as throwing him a ball or putting him through hoops. This way the dolphin can learn multiple tricks.

In this “Underwater Exploration” mode, the dolphin explores the underwater world. The player can control it as they see fit through the environment, represented by the map on the upper screen. The place is in the form of a maze, and the dolphin can pick up certain particular objects there.
Additionally, he may meet other sea creatures who will ask him to solve their problems. In addition to these elements, the player can also take photos of the animals they encounter.