Ethno - hydrography - is a study of Ivatan beliefs and practices about ocean water behaviors. It embraces the study of the rhythm of the tides, the pattern of currents anf the behavior of the water waves within Batanes islands, particularly around Batan Island.

Ethno - hydrography Beliefs:

1. The moon rises about an hour later at night.

Explanation: The moon rises 50 minutes later each night. This being so, makes the calculation of fishers of about an hour to be very close.

2. Low/hide tide is observed daily. It occurs an hour later following the motion of the moon.

Explanation: The moon influences the waters and causes the tides.

3. Currents at Balintang channel are usually strong. Navigating small vessels experience rough seas especially during the southwest Monsoon.

Explanation: During southwest monsoon, the currents at Balintang channel reach a velocity of 3 knots and become erratic.

4. Shallow portions in the water produce turbulence on the surface which is dangerous to sea crafts, and so they must be evaded.

Explanation: Shallow portions in the water are due to the elevations in the seafloor. Waters surrounding the areas rush towards the shallow portions causing waves of greater amplitude.

5. “Chinahan” is the best time to cross the sea in between the islands.

Explanation: “Chinahan” means slack water which has a velocity equal to zero. It happens when two opposing waves meet and terminate each other.

6. Reversing currents are more often experienced in between Sabtang, Ivana and Adekey.

Explanation: Reversing currents are caused by reflection of the water as they hit barriers.

7. There are two periodic currents that accompany the rise and fall of tide. These are “Amteng” and “Isaak” Currents.

Explanation: Periodic currents are tidal currents and they occur because of the change in tides.

8. The general direction of the vessels drifted by the current is towards China or Taiwan on the north.

Explanation: Currents can drift vessels. Such currents are caused by the general circulatory system of the world’s oceans. Like the Kuroshio and Equatorial currents which are classified as permanent currents. They both move northward within the Tropic of Cancer due to Earth’s rotation.

9. There are two high tides and two low tides in a day. If the lowest low tide occurs 3:00 PM, the first one must occurred at the same time in the early morning.

Explanation: The gravitational force of the moon on earth causes two bulges of water simultaneously occurring. One is caused by the direct influence of the moon and is called “direct tide”; the other in the opposite end is caused by the centrifugal force due to the earth’s rotation.

10. The lowest low tide takes place every full moon and new moon, when the moon is exactly overhead.

Explanation:The rotation of the earth tends to carry the tidal bulge forward of their position in a direct line with the moon. As a result, high tides do not occur until several hours after the moon is overhead.

11. Fishing during full moon is avoided because of poor catch.

Explanation: During full moon, the wind and current become relatively stronger, particularly during the southwest and the northeast monsoons. These conditions make the fishing operation difficult. Also, a full moon makes the surrounding bright by dispersing light. If a fishing gear that makes use of a weak ordinary light is employed, no fish will be become attracted to it because the light is not concentrated.

Ethno - Agricultural Beliefs - is a study of Ivatan beliefs and practices about farming.

Ethno - Agricultural Beliefs and Practices:

1. "Avayat" (West wind)

      - Harvesting banana and citrus fruit is not advisable during west wind. Likewise, strong crops (rice, corn, garlic, and other root crops) are prevented because accordingly, mealy bug infestation occurs and agricultural products easily get spoiled. Farmers also refrain from weeding their farms during west wind.

Explanation: The beliefs and practices in relation to west wind direction has something to do with the humidity of the atmosphere combined with strong sea sprays thus affecting generally those agricultural products to rot.

2. Covering “Laveng” with “Vula” leaves (Colocacia macrohriza Linn.)

     - "Laveng" is a farming practice usually employed to yam and spiny yam, which is done after preparing the seed-pieces intended for planting division. It is a pit-like structure about one and a half foot deep and one meter long. After the seedpieces have been prepared “vinadtak”, these are nicely arranged in the “laveng” in a pile structure. After this process, it shall be covered with “vula” leaves prior to covering with surface soil.

Explanation: The leaves serve as protector from too much moisture during heavy rains and provide warmer temperature to heal the wounds of seed-pieces. It also prevents them from the attack of soil pathogens.

3. "Kapanavun su atngeh nu muhamuha" (Hilling-up)

      - Hilling-up as a farming practice is done simultaneously with weeding and cultivation. This is accomplished by loosening the soil around the plants, followed by scraping it towards the basal portion of the plant forming a mound-like structure.

Explanation: It provides good soil tilth, aeration, and adequate area for storing moisture during rainfall, expansion of tubers and good establishment of roots to prevent plants from lodging during strong winds.

4. "Maytutu du ñisañisan" (cutting of branches of trees along the sides or borders of the farm area)

      - Farmers practiced cutting of branches of trees in all sides of the farm area usually done before or just after planting. This practice is employed with the belief that sunlight is very important to the growth and development of the crops.

Explanation: This is practiced to prevent the plants from suffering stress of etiolating or the discoloration of the leaves of the plant due to sunlight deficiency which affect the photosynthetic activity of the plants.

Ethno – Climatic Beliefs - is a study of Ivatan beliefs and practices about weather forecasting.

Ethno – Climatic Beliefs:

5. When the color of the sunset is intensely orange, in 2-3 days time, a typhoon will come.

Explanation: When a typhoon is about to come, its winds can already be felt even if it has not yet reach a particular place. And because of this, dust particles and soot particles spread into the atmosphere scattering the rays of the sun making the whole sky painted yellow red or orange.

6. Ivatans say that when the native orchid “kaduday” and the native daffodils plants bloom, they bring not only rain but most of the time storm.

Explanation: The native orchid only blooms during rainy season because this is its flowering time. Same is true with the native daffodils.

7. When winged ants come out, it foretells rain.

Explanation: Ants have the ability to sense when rainy season is approaching and when this time comes, they take their food and head for shelter.

8. When “aryes” and palomaria trees along the roads and farms bear shoots usually foretell the coming of rains and winds.

Explanation: These trees can only bear and produce shoots during windy and rainy weather because this is where they can adapt. That is why the “aryes” is a very strong tree particularly during tropical storm. It is because they have adapted to the weather for they only bear shoots when winds and rain comes

9. When the moon forms a halo or a “corona” around it, this illustrates observable fact that there would be a strong current on the following day.

Explanation: The ice crystals that cover the halo signify high altitude, thin cirrus clouds that normally precede a warm front by one or two days. Typically, a warm front will be associated with a low pressure system which is commonly referred to as a storm.

Ethno-Agricultural Beliefs:

1. It is mostly appropriate to plant during high tide to ensure a good harvest.

Explanation: High tide raises the water table. This enables the plants to this increase the amount of water available to the plant. Thus, planting crops that require water like root crops, and rice may bring about a good harvest.

Ethno-Pediatric Beliefs:

1. Do not take too much sweet food during pregnancy period.

Explanation: Pregnant mothers are prevented from eating sweet foods or other energy-rich foods only if they are diabetic. Diabetes, whether appearing only before the pregnancy or before it, may result in the development of characteristically big babies. Fetal size is one of the crucial determinants in vaginal birth.

2. Walking the woman around the house to empty her water bag during labor is supposed to ease childbirth.

Explanation: Walking stimulates uterine contractions. When the contractions become active, the pressure becomes strong enough to cause progressive rapid cervical dilatation. Sometimes, the water bag incidentally ruptures as a result of the contractions. As the water or amniotic fluid, begins to come out, the baby is forced to come out also. Rupturing of the water bag is preferred when the opening of the cervix starts to reach 6 centimeters wide and the mother is expected to deliver within a few hours. Otherwise, a too early rupture will expose the baby to an unsterile environment where he/she may become infected.

Other Beliefs:

1. Ivatans avoid ironing clothes while in an open air.

Explanation: Anyone working in an occupation such as ironing, in which they extensively use their hands is said to be prone to pasma. From the traditional cause of "init" and "lamig", this is a traditional concept sufficiently intact in the contemporary Philippine psyche to be accepted, alone as a cause for pasma.

2. Whenever faunas such as snakes and insects from the Mt. Iraya descend to the community, a volcanic eruption is expected to happen.

Explanation: Swelling of the volcano signals that magma has accumulated near the surface causing the rise of soil temperature and so these faunas tend to leave the mountain.

3. Mothers who newly delivered a baby aren’t allowed to read for they’ll experience aches.

Explanation: Because of the mother’s drain labor, they still cannot regain their normal health status and so they can easily get tired and dizzy.

4. Mothers who delivered their babies at home wear binders “tahed”.

Explanation: This supports the lower abdomen of the mother due to the expansion of it and to bring back the hip bone to its normal position.