## 1 Introduction
Thus, to avoid the empty region, multiple parameters need to be considered for forwarding the data packets in a well-disciplined manner. Hence, energy-efficient routing schemes are required, which have the ability to take robust short and quick routing paths between source and master stations and also avoid empty regions. To make the scheme energy efficient, geographic routing [9] is best suited as it is frequently used due to its scalability and simplicity; also, it does not need and complete route information between two junctions. Angle-based routing is easily coped with transmitting data by circling more multiple neighbors' nodes by computing the angles. For this, priorities are defined for different parameters like the shortest distance and energy. The nodes with the highest priority receive the data and are able to send it further. The rest of the node does not receive data because acknowledgment is received with the highest priority nodes. Furthermore, geographical routing has a major reason to create the empty region because one node at a time is selected for transmission, and angle-based routing selects those nodes that cover with angle cone, but it consumes a lot of time and energy to compute the angle with every flooding spell. In this way, both routing schemes need to work together to cope with multiple parameters to improve energy and avoidance of empty regions. Our Contributions. Motivated by the above consideration of energy-efficient and angle-based scenarios [6; 7], we proposed the Tri-Angular Nearest Vector-Based Energy Efficient Routing (TANVEER) with its three sub-sections having exclusive features like layer-based adjustment, data-packet delivery, and binary internodes. The TANVEER, by nature, uses both angle and energy-efficient approaches for reliable communication. The layer-based adjustment of TANVEER, (LBA-TANVEER) first assigns the IDs of the nodes to all deployed nodes in the form of layers from anchored to surface of the water so that each node is easily identified with its status to detection of empty node or group of empty nodes called empty regions. All the adjustments of layers will be static throughout the network's lifetime. Secondly, the immediate data packet delivery (DPD-TANVEER) starts whenever the empty regions are detected; the recovery process of data is done by binary inter nodes (BIN-TANVEER). The BIN is presented with the novel nodes called watchman nodes that enable data recovery from the empty regions based on the nearest vector angle is made. The contribution of our proposed scheme is given as follows: The TANVEER summarizes three metrics (three sides of angle calculation, energy, and the number of nodes) to select the nearest vector with a triangular approach to forwarding the data packets towards the sink. It selects the node which is closest to the nearest vector by flooding the tri-angular zone and finds out the closest path for the destination. The data are forwarded in the form of layer by layer manner so that each layer maintains the traffic smoothly before and after the communication. The LBA-TANVEER uses the multi-sink architecture at the surface of the water, while the topmost layer consists of ordinary sensor nodes. The watchman node with both left-right directions to rescue the empty regions are present in each layer. The DPD-TANVEER uses the same path provided by the LBA-TANVEER. The BIN-TANVEER adjusts the watchman nodes and follows the empty region's occurrence and transfers the data through BIN towards sink through bypass the empty regions successfully. The BIN is only active when it needs, while the rest of the time, it just monitors the occurrence of empty nodes. The rest of the paper is organized as the related latest underwater routing schemes are described in Section 2. The problem is explained in Section 3, while the proposed model and TANVEER are described in Sections 4 and 5, respectively. Sections 6-8 deal with the proposed LBA-TANVEER, DPD-TANVEER, and BIN-TANVEER.