Q. Is it permitted to take (during the Nine Days) a boat ride on the lake without getting wet? Is it permitted if you do it for the children?

A. Poskim advise that during the period of Ben Hametzarim and especially during the Nine Days one should abstain from engaging in activities that involve any danger, since at this time the Mazal of our nation is not auspicious. (Mekor Chaim 551: 14, Peas Hasadeh 1: 10, Teshuvos V’Hanhagos 2:263). See also Piskei Teshuvos 6 p. 68 in regards to avoiding scheduling medical operations in those days and Orchois Rabbenu (2: p. 129) and Vedorashto Vechokarto (O.H. 90) as to traveling during that time.
Horav Shlomo Miller’s Shlit’a opinion is that besides the above reason, during the Nine Days one should maintain a certain decorum and demureness in one’s activities that follows the spirit of mourning for the Beis Hamikdosh. That is also the example to be given to our children.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a