TODAY | November 07, 2013
>>> new additions, sumatran tiger cobbs, they had their first debut. the public could get their first view very soon. more from the smithsonian national zoo .
>> reporter: nbc news got a look at the newest kittens, experiencing water for the first time and preparing for a very important milestone.
>> for us humans, i would relate to to the first day opening.
>> reporter: zoo staff dropped the tiger cubs into the outside moat, where they have never been before. first up the male, then his sister's turn. while it's cute, this dip is serious. it's a swim reliability test. the gel to make sure the cubs can get themselves out of the water a. key factor in whether they are ready to go on pub leg display.
>> what we want them to show us is they have that instinct to get out of a dangerous situation.
>> everybody did very well.
>> reporter: caring for the cubs is a top priority. sumtran tigers are critically dangered. the cubs born in august are healthy and enjoy playtime with each other and their mom. and now the entire zoo is celebrating. a day of success in uncharted water . for "today," kristen welker, nbc news, walk.