The first conditional with si
When you want to talk about a realistic condition and its likely result—like what happens when you head out into the open sea—you can use si ("if"). This is known as the first conditional.
To form these sentences, use si followed by a verb in the present tense for the condition. For the result, you can also use the present tense to state a fact or a general truth.
| If the wind is good, my father sails today. | Si el viento es bueno, mi padre navega hoy. |
| If the wave is very big, the boat sinks. | Si la ola es muy grande, el barco se hunde. |
Giving commands with si
If you want to tell someone what to do when a specific condition is met, you can use an imperative (a command) in the result part of the sentence. The verb right after si still stays in the present tense.
| If you want to sail, come with me. | Si quieres navegar, ven conmigo. |
| If the boat sinks, get off the boat. | Si el barco se hunde, sal del barco. |
| If you get seasick, go to bed. | Si te mareas, ve a la cama. |
Changing the sentence order
Just like in English, the si clause doesn't have to go at the beginning. You can put the result first and the condition second. Notice that when you start with the si clause, a comma separates the two parts of the sentence. When si comes in the middle, you drop the comma.
| The stone sinks if you put it in the sea. | La piedra se hunde si la pones en el mar. |
| Put the compass on the table if we go to the sea. | Pon la brújula en la mesa si vamos al mar. |
| Go to the coast if you see the lighthouse. | Ve a la costa si ves el faro. |