If one does not have a utensil with which to wash Netilat Yadayim in the morning, but he has access to a river or sea, or a Mikveh, he should dip his hands three times in that body of water, and he may then recite Berachot and pray. However, he should not recite a Beracha over this washing, since it is uncertain whether one can fulfill the obligation by washing in this fashion. According to some opinions, the impure forces that descend upon one's hands during the night can be removed only with a utensil pouring water on them three times, and dipping one's hands – even into a natural body of water or Halachically-valid Mikveh – does not suffice. Given the concern that this washing might thus be invalid, one should not recite a Beracha when washing in this fashion. And, when he later has access to a utensil, he should wash properly with the utensil, but without reciting a Beracha, as he may have fulfilled his requirement with his initial washing.
This applies also to one whose only option is to dip his hands in snow. He should dip his hands three times in the snow, but without reciting a Beracha, and he should wash his hands properly later when he has access to a utensil.