At times, immersion in a mikvah is a mitzvah, and it warrants a blessing, like any other.

The Blessing Before Immersing Dishes

Before immersing newly acquired vessels made of metal or glass, the following blessing is said:

Blessed are You, L‑rd our G‑d, King of the Universe, Who has sanctified us with His commandments, and commanded us concerning the immersion of a vessel (vessels)

בָּרוּךְ אַתָּה ה' אֱלֹהֵינוּ מֶלֶךְ הָעוֹלָם אֲשֶׁר קִדְּשָׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ עַל טְבִילַת כֶּלִי / כֵּלִים

Bah-rookh ah-tah ah-doh-noi eh-loh-hay-noo meh-lekh hah-oh-lahm ah-sher ki-deh-shah-noo be-mitz-voh-tahv veh-tzee-vah-noo ahl teh-vee-laht keh-lee (kay-leem)

Note that one blessing (appropriately modified) is sufficient for numerous dishes.

When a Married Woman or Convert Immerses

Married Jewish women immerse in a mikvah following the niddah period, before resuming intimate relations with their husbands. While her body is submerged in the water, she covers her head, hugs her chest, and says the following:

Blessed are You, L‑rd our G‑d, King of the Universe, Who has sanctified us with His commandments, and commanded us concerning the immersion

בָּרוּךְ אַתָּה אֲדֹנָי אֱלֹהֵינוּ מֶלֶךְ הָעוֹלָם, אֲשֶׁר קְדְּשָׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ עַל הַטְּבִילָה

Bah-rookh ah-tah ah-doh-noi eh-loh-hay-noo meh-lekh ha-oh-lahm ah-sher ki-deh-shah-noo be-mitz-voh-tahv veh-tzee-vah-noo ahl hah-teh-vee-lah

This blessing is often posted prominently at the site of the mikvah, and is also said before a person immerses as part of the conversion process.